@TechReport{Dartmouth:TR2000-362,
  author = {Chris Bailey-Kellogg and John J. Kelley and Clifford Stein and Bruce Randall Donald},
  title = {{Reducing Mass Degeneracy in SAR by MS by Stable Isotopic Labeling}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-362},
  year = {2000},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-362.ps.Z},
  comment = {
    This report supercedes <A HREF="http://www.cs.dartmouth.edu/reports/abstracts/TR99-359/">TR99-359</A>.
         To appear in the <a href="http://ismb00.sdsc.edu/">8th
    International Conference on Intelligent Systems for Molecular Biology</a>,
    (August 20-23, 2000) La Jolla, CA (Accepted; in press).
  },
  abstract = {
    Mass spectrometry (MS) promises to be an invaluable tool for
    functional genomics, by supporting low-cost, high-throughput
    experiments.  However, large-scale MS faces the potential problem of
    mass degeneracy -- indistinguishable masses for multiple
    biopolymer fragments (e.g. from a limited proteolytic digest).  This
    paper studies the tasks of planning and interpreting MS experiments
    that use selective isotopic labeling, thereby substantially reducing
    potential mass degeneracy.  Our algorithms support an
    experimental-computational protocol called Structure-Activity
    Relation by Mass Spectrometry (SAR by MS), for elucidating the
    function of protein-DNA and protein-protein complexes.  SAR by MS
    enzymatically cleaves a crosslinked complex and analyzes the resulting
    mass spectrum for mass peaks of hypothesized fragments.  Depending on
    binding mode, some cleavage sites will be shielded; the absence of
    anticipated peaks implicates corresponding fragments as either part of
    the interaction region or inaccessible due to conformational change
    upon binding.  Thus different mass spectra provide evidence for
    different structure-activity relations.  We address combinatorial and
    algorithmic questions in the areas of data analysis
    (constraining binding mode based on mass signature) and
    experiment planning (determining an isotopic labeling strategy to
    reduce mass degeneracy and aid data analysis).  We explore the
    computational complexity of these problems, obtaining upper and lower
    bounds.  We report experimental results from implementations of our
    algorithms.
  }
}

@TechReport{Dartmouth:TR2000-363,
  author = {Jon Howell and David Kotz},
  title = {{A Formal Semantics for SPKI}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-363},
  year = {2000},
  month = {March},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-363.ps.Z},
  comment = {
    This TR supercedes TR1999-361.
    This technical report is an extended version of a paper submitted to
    ESORICS 2000.
    For more information, see the <A href="http://www.cs.dartmouth.edu/~jonh/research/delegation/">project web page</A>.
  },
  abstract = {
    We extend the logic and semantics of authorization due to
    Abadi, Lampson, et al. to support restricted delegation.
    Our formal model provides a simple interpretation for the variety of
    constructs in the Simple Public Key Infrastructure (SPKI), and
    lends intuition about possible extensions. We discuss both extensions
    that our semantics supports and extensions that it cautions against.
  }
}

@TechReport{Dartmouth:TR2000-364,
  author = {Jon Howell and Keith Kotay},
  title = {{Landmarks for absolute localization}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-364},
  year = {2000},
  month = {March},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-364.ps.Z},
  comment = {
    This document describes work done in the Dartmouth Robotics Laboratory
    in April of 1997 and August of 1999. It was previously ``published'' as
    a web page, but we thought it would make sense to document it more
    permanently.
  },
  abstract = {
    For certain experiments in mobile robotics, it is convenient to eliminate
    positional estimation error in the interest of analyzing other parts of
    the experiment. We designed and implemented a simple, accurate scheme
    for encoding and recovering absolute position information. The encoding
    is a two-dimensional image printed on the plane of the floor, and the
    absolute position information is recovered using a downward-looking
    video camera mounted on a mobile robot.
  }
}

@TechReport{Dartmouth:TR2000-365,
  author = {Robert S. Gray and David Kotz and George Cybenko and Daniela Rus},
  title = {{Mobile Agents: Motivations and State-of-the-Art Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-365},
  year = {2000},
  month = {April},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-365.ps.Z},
  comment = {
    This technical report will appear as a chapter in Jeffrey M. Bradshaw,
    editor, Handbook of Agent Technology, AAAI/MIT Press, 2000.  In Press.
  },
  abstract = {
    A mobile agent is an executing program that can migrate, at times of its
    own choosing, from machine to machine in a heterogeneous network.  On
    each machine, the agent interacts with stationary service agents and
    other resources to accomplish its task.  In this chapter, we first make
    the case for mobile agents, discussing six strengths of mobile agents
    and the applications that benefit from these strengths.  Although none of
    these strengths are unique to mobile agents, no
    competing technique shares all six.  In other words, a mobile-agent
    system provides a single general framework in which a wide range of
    distributed applications can be implemented efficiently and easily.
    We then present a representative cross-section of current mobile-agent
    systems.
  }
}

@TechReport{Dartmouth:TR2000-366,
  author = {David Kotz and Guofei Jiang and Robert S. Gray and George Cybenko and Ronald A. Peterson},
  title = {{Performance Analysis of Mobile Agents for Filtering Data Streams on Wireless Networks}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-366},
  year = {2000},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-366.ps.Z},
  comment = {
    In August 2000 a revised version appeared in the International
    Workshop on Modeling and Simulation of Wireless and Mobile Systems
    (MSWiM 2000).  In October 2000 a further revised version appeared as
    Dartmouth Technical Report TR2000-377, and was submitted to the
    journal Mobile Networks and Applications (ACM MONET).
  },
  abstract = {
    Wireless networks are an ideal environment for mobile agents, because
    their mobility allows them to move across an unreliable link to reside
    on a wired host, next to or closer to the resources they need to use.
    Furthermore, client-specific data transformations can be moved across
    the wireless link, and run on a wired gateway server, with the goal of
    reducing bandwidth demands.  In this paper we examine the tradeoffs
    faced when deciding whether to use mobile agents to support a
    data-filtering application, in which numerous wireless clients filter
    information from a large data stream arriving across the wired
    network.  We develop an analytical model and use parameters from our
    own experiments to explore the model's implications.
  }
}

@TechReport{Dartmouth:TR2000-367,
  author = {Cliff Stein and David P. Wagner},
  title = {{Approximation Algorithms for the Minimum Bends Traveling Salesman Problem}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-367},
  year = {2000},
  month = {April},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-367.ps.Z},
  comment = {
    Submitted to FOCS 2000.
  },
  abstract = {
      The problem of traversing a set of points in the order that minimizes
    the total distance traveled (traveling salesman problem) is one of
    the most famous and well-studied problems in combinatorial
    optimization.  It has many applications, and has been a testbed for
    many of the must useful ideas  in algorithm design and analysis.  The
    usual metric, minimizing the total distance traveled, is an important
    one, but many other metrics are of interest.
      In this paper, we introduce the metric of minimizing the number of
    turns in the tour, given that the input points are in the Euclidean
    plane.  To our knowledge this metric has not been studied previously.
    It is motivated by applications in robotics and in the movement of
    other heavy machinery: for many such devices turning is an expensive
    operation.  We give approximation algorithms for several variants
    of the traveling salesman problem for which the metric is to minimize
    the number of turns.  We call this the minimum bends traveling salesman
    problem.
      For the case of an arbitrary set of $n$ points in the
    Euclidean plane, we give an O(lg z)-approximation algorithm, where
    z is the maximum number of collinear points.  In the worst case z
    can be as big as n, but z will often be much smaller.  For the case
    when the lines are restricted to being either horizontal or vertical,
    we give a 2-approximation algorithm.  If we have the further
    restriction that no two points are allowed to have the same x- or
    y-coordinate, we give an algorithm that finds a tour which makes at
    most two turns more than the optimal tour.  Thus we have an
    approximation algorithm with an additive, rather than a multiplicative
    error bound.  Beyond the additive error bound, our algorithm for this
    problem introduces several interesting algorithmic techniques for
    decomposing sets of points in the Euclidean plane that we believe
    to be of independent interest.
  }
}

@TechReport{Dartmouth:TR2000-368,
  author = {Eric Michael Greenberg},
  title = {{A Simulation of Auroral Absorption}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-368},
  year = {2000},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-368.pdf},
  comment = {
    Advisor: Dan Rockmore
  },
  abstract = {
    HF radio transmissions propagate long distances by reflecting off the ionosphere.  At high latitudes radio propagation is strongly affected by the northern lights (aurora borealis), which causes ionization at low altitudes and hence the absorption of radio waves.  Models of this process are still in a primitive state.  A simulation of radio wave propagation was created in order to test Foppiano and Bradley's empirical model of auroral absorption.  The simulation attempts to predict the net absorption of signals at a receiver by simulating a large number of transmitters, even though the exact sources of the signals are unknown.  Although the simulation takes into account auroral and nonauroral absorption as well as other sources of path loss, the analysis focuses on the nighttime aurora.  An intelligent search algorithm is used in order to efficiently adjust the model to best fit the data.  The output of the simulation is qualitatively and quantitatively compared to signal levels observed with HF radio receivers located in northern Canada.  The analysis allows us to develop alternative models of auroral absorption which account for the level of geomagnetic activity, and these are compared to the standard Foppiano and Bradley model.
  }
}

@TechReport{Dartmouth:TR2000-369,
  author = {Karolyn A. Abram},
  title = {{Registration of Images with Dissimilar Contrast using a  Hybrid Method Employing Correlation and Mutual Information}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-369},
  year = {2000},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-369.ps.Z},
  comment = {
    Undergraduate Honors Thesis
    Advisor: Daniel N. Rockmore
  },
  abstract = {
    The problem of fitting one image into another is commonly
    called "registration."  Finding the best possible translation and rotation
    necessary to align two images is one approach to solving this problem.
    Registration is a crucial component of many remote sensing and medical
    image interpretation applications.  Image alignment techniques aid in
    volumetric estimations of complicated structures and allow
    radiologists to accurately identify changes between sequential images.
    Radiologists require image alignment capabilities to correct for
    patient motion and/or content displacement between images.
         Numerous image registration techniques exist for correcting the
    alignment problems mentioned above.  Unfortunately, most of these
    techniques, such as Correlation, fail to find a good alignment when
    dealing with images that differ in contrast.  The Mutual Information
    method is able to align images independently of contrast, but it is
    computationally intensive.  We explore a hybrid technique that
    utilizes both Correlation and Mutual Information.  The Hybrid
    technique hopes to gain greater contrast independence than Correlation
    alone while achieving a lower running time than a pure Mutual
    Information technique.
  }
}

@TechReport{Dartmouth:TR2000-370,
  author = {Debbie O. Chyi},
  title = {{An Infrastructure for a Mobile-Agent System that Provides  Personalized Services to Mobile Devices}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-370},
  year = {2000},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-370.ps.Z},
  comment = {
    Undergraduate Honors Thesis.
    Advisor: David F. Kotz
  },
  abstract = {
          In this paper, we present the design of a mobile-agent system 
    that provides a mobile user with a personalized information retrieval 
    service and we describe the implementation of the infrastructure for 
    such a system.  This "Personal Agent System" gathers information from 
    the Internet and uses context-aware mechanisms to manage the 
    information according to a mobile user's needs and preferences.  The 
    user's schedule and location are the context indicators in this 
    system.  These indicators are critical in ensuring that users obtain 
    only the information they want, receive information in a form that is 
    most useful for viewing on their mobile device, and is notified of 
    new information in a minimally intrusive manner.  The system 
    incorporates a rule-based learning system to enhance the 
    personalization achieved by the system.
  }
}

@TechReport{Dartmouth:TR2000-372,
  author = {John C. Artz},
  title = {{Personal Radio}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-372},
  year = {2000},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-372.ps.Z},
  comment = {
    Undergraduate Honors Thesis.
    Advisors: David Kotz and Daniela Rus
  },
  abstract = {
    With the development of new technologies that allow the broadcast of 
    digital data over radio signals, there are many possibilities for 
    improving upon the traditional radio station model for content 
    delivery. The idea of Personal Radio is a system that tailors content 
    to meet the needs of each individual. Using Global Positioning System 
    (GPS) technology to play location specific content, the listening 
    history to play content an appropriate number of times, and user 
    feedback to learn personal preferences, the Personal Radio provides 
    the listener with the content that is the most useful/interesting to 
    them. This paper will examine the general design of such a system and 
    present solutions developed in the implementation of several pieces 
    of the design.
  }
}

@TechReport{Dartmouth:TR2000-373,
  author = {David B. Martin},
  title = {{Depth from Flash}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-373},
  year = {2000},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-373.ps.Z},
  comment = {
    Undergraduate Honors Thesis.
    Advisor: Hany Farid
  },
  abstract = {
    Digital camera technology has recently seen substantial
    improvements in image quality while lower prices have made
    it affordable to the average consumer. Camera manufacturers,
    however, are not taking full advantage of this new medium
    for image capture.  By filtering the already digitized image
    produced by these cameras through on-board image processing
    algorithms we can dramatically increase the power of digital
    cameras.  For example, according to experts in the
    photographic industry, most people simply take bad
    pictures. Classic examples of this phenomenon are
    photographs taken indoors with a point-and-shoot style
    camera using its built-in flash.  The subjects of these
    photographs often seem to have a spotlight on them, making
    them look bright and washed out while the rest of the
    photograph is dark and indistinct. This can primarily be
    accounted for by a well known property of point light
    sources: falloff in brightness is inversely proportional to
    the square of the distance between the light and the object
    being illuminated. A technique first introduced in the field
    of computer vision has been shown to successfully recover
    information about the distance between the light source and
    objects in the world. We propose using this technique, which
    is readily implementable in hardware, to correct for a
    variety of poorly illuminated digital images.
  }
}

@TechReport{Dartmouth:TR2000-375,
  author = {Ezra E. K. Cooper and Robert S. Gray},
  title = {{An Economic CPU-Time Market for D'Agents}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-375},
  year = {2000},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-375.ps.Z},
  comment = {
    Undergraduate honors thesis.
    Advisor: Bob Gray.
  },
  abstract = {
    A usable and efficient resource-management system has been created for
    use with D'Agents. The software dynamically negotiates a price rate for
    CPU time, using the competitive bids of mobile agents that offer
    currency in return for fast computation. The system allows mobile agents
    to plan their expenditures across many hosts while minimizing the time
    needed for their tasks. The ability to price CPU time opens the door for
    service owners to be compensated for the computation consumed by agents and
    provides an incentive for servers to allow anonymous agents. We
    discuss the theoretical background which makes a CPU market system
    possible and the performance of the D'Agents market system.
  }
}

@TechReport{Dartmouth:TR2000-376,
  author = {Martin Mundhenk},
  title = {{The complexity of planning with  partially-observable Markov decision processes}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-376},
  year = {2000},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-376.ps.Z},
  abstract = {
    This work surveys results on the complexity of planning under
    uncertainty. The planning model considered is the partially-observable
    Markov decision process. The general planning problems are, 
    given such a process,
    (a) to calculate its performance under a given control policy,
    (b) to find an optimal or approximate optimal control policy, and
    (c) to decide whether a good policy exists.
    The complexity of this and related problems
    depend on a variety of factors,
    including the observability of the process state,  
    the compactness of the process representation,
    the type of policy, or
    even the number of actions relative to the number of states.
    In most cases, the problem can be shown to be
    complete for some known complexity class.
      The skeleton of this survey are results from 
    Littman, Goldsmith and Mundhenk (Journal of Artificial Intelligence
    Research 1998), Mundhenk (Mathematics of Operations Research 2000),
    Mundhenk, Goldsmith, Lusena and Allender (Journal of the ACM 2000),
    and Lusena, Goldsmith and Mundhenk (University of KY CS TR).
    But there are also some news.
  }
}

@TechReport{Dartmouth:TR2000-377,
  author = {David Kotz and George Cybenko and Robert S. Gray and Guofei Jiang and Ronald A. Peterson and Martin O. Hofmann and Daria A. Chacon and Kenneth R. Whitebread and James Hendler},
  title = {{Performance Analysis of Mobile Agents for Filtering  Data Streams on Wireless Networks}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-377},
  year = {2000},
  month = {October},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-377.ps.Z},
  comment = {
    Updated version of TR2000-366.  To appear, after revisions, in the journal
    Mobile Networks and Applications (ACM MONET).
  },
  abstract = {
    Wireless networks are an ideal environment for mobile agents, since their 
    mobility allows them to move across an unreliable link to reside on a wired 
    host, next to or closer to the resources that they need to use.  Furthermore, 
    client-specific data transformations can be moved across the wireless link and
    run on a wired gateway server, reducing bandwidth demands.  In
    this paper we examine the tradeoffs faced when deciding whether to use mobile 
    agents in a data-filtering application where numerous wireless clients filter 
    information from a large data stream arriving across the wired network.  We
    develop an analytical model and use parameters from filtering experiments 
    conducted during a U.S. Navy Fleet Battle Experiment (FBE) to explore the
    model's implications.
  }
}

@TechReport{Dartmouth:TR2000-378,
  author = {Jon Howell},
  title = {{Naming and sharing resources across administrative boundaries (Volume I)}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-378},
  year = {2000},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-378.ps.Z},
  comment = {
    This technical report represents Volume One of the dissertation.  Volume
    One (187 pages) is the heart of the dissertation. Volume Two (237
    pages) contains a software manual introduced with illustrated code
    fragments, plus plots of the raw data used for the experimental
    results presented in Volume One. That material is optional; I
    recommend that the interested reader begin with just Volume One.
    Volume II is available as TR2000-379.  
      Please note that a list of errata is available as TR2000-380.
  },
  abstract = {
      I tackle the problem of naming and sharing resources across
    administrative boundaries. Conventional systems manifest the hierarchy
    of typical administrative structure in the structure of their own
    mechanism.  While natural for communication that follows hierarchical
    patterns, such systems interfere with naming and sharing that cross
    administrative boundaries, and therefore cause headaches for both users
    and administrators.  I propose to organize resource naming and
    security, not around administrative domains, but around the sharing
    patterns of users.
      The dissertation is organized into four main parts.  First, I discuss
    the challenges and tradeoffs involved in naming resources and consider
    a variety of existing approaches to naming.
      Second, I consider the architectural requirements for user-centric
    sharing. I evaluate existing systems with respect to these
    requirements.
      Third, to support the sharing architecture, I develop a formal logic of
    sharing that captures the notion of restricted delegation.  Restricted
    delegation ensures that users can use the same mechanisms to share
    resources consistently, regardless of the origin of the resource, or
    with whom the user wishes to share the resource next.  A formal
    semantics gives unambiguous meaning to the logic.  I apply the
    formalism to the Simple Public Key Infrastructure and discuss how the
    formalism either supports or discourages potential extensions to such a
    system.
      Finally, I use the formalism to drive a user-centric sharing
    implementation for distributed systems.  I show how this implementation
    enables end-to-end authorization, a feature that makes heterogeneous
    distributed systems more secure and easier to audit.  Conventionally,
    gateway services that bridge administrative domains, add abstraction,
    or translate protocols typically impede the flow of authorization
    information from client to server. In contrast, end-to-end
    authorization enables us to build gateway services that preserve
    authorization information, hence we reduce the size of the trusted
    computing base and enable more effective auditing.  I demonstrate my
    implementation and show how it enables end-to-end authorization across
    various boundaries.  I measure my implementation and argue that its
    performance tracks that of similar authorization mechanisms without
    end-to-end structure.
      I conclude that my user-centric philosophy of naming and sharing
    benefits both users and administrators.
  }
}

@TechReport{Dartmouth:TR2000-379,
  author = {Jon Howell},
  title = {{Naming and sharing resources across administrative boundaries (Volume II)}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-379},
  year = {2000},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-379.ps.Z},
  comment = {
    This technical report represents Volume Two of the dissertation.  Volume
    One (187 pages) is the heart of the dissertation. Volume Two (237
    pages) contains a software manual introduced with illustrated code
    fragments, plus plots of the raw data used for the experimental
    results presented in Volume One. That material is optional; I
    recommend that the interested reader begin with just Volume One.
    Volume I is available as TR2000-378.  
      Please note that a list of errata is available as TR2000-380.
  },
  abstract = {
      I tackle the problem of naming and sharing resources across
    administrative boundaries. Conventional systems manifest the hierarchy
    of typical administrative structure in the structure of their own
    mechanism.  While natural for communication that follows hierarchical
    patterns, such systems interfere with naming and sharing that cross
    administrative boundaries, and therefore cause headaches for both users
    and administrators.  I propose to organize resource naming and
    security, not around administrative domains, but around the sharing
    patterns of users.
      The dissertation is organized into four main parts.  First, I discuss
    the challenges and tradeoffs involved in naming resources and consider
    a variety of existing approaches to naming.
      Second, I consider the architectural requirements for user-centric
    sharing. I evaluate existing systems with respect to these
    requirements.
      Third, to support the sharing architecture, I develop a formal logic of
    sharing that captures the notion of restricted delegation.  Restricted
    delegation ensures that users can use the same mechanisms to share
    resources consistently, regardless of the origin of the resource, or
    with whom the user wishes to share the resource next.  A formal
    semantics gives unambiguous meaning to the logic.  I apply the
    formalism to the Simple Public Key Infrastructure and discuss how the
    formalism either supports or discourages potential extensions to such a
    system.
      Finally, I use the formalism to drive a user-centric sharing
    implementation for distributed systems.  I show how this implementation
    enables end-to-end authorization, a feature that makes heterogeneous
    distributed systems more secure and easier to audit.  Conventionally,
    gateway services that bridge administrative domains, add abstraction,
    or translate protocols typically impede the flow of authorization
    information from client to server. In contrast, end-to-end
    authorization enables us to build gateway services that preserve
    authorization information, hence we reduce the size of the trusted
    computing base and enable more effective auditing.  I demonstrate my
    implementation and show how it enables end-to-end authorization across
    various boundaries.  I measure my implementation and argue that its
    performance tracks that of similar authorization mechanisms without
    end-to-end structure.
      I conclude that my user-centric philosophy of naming and sharing
    benefits both users and administrators.
  }
}

@TechReport{Dartmouth:TR2000-380,
  author = {Jon Howell},
  title = {{Naming and sharing resources across administrative boundaries (errata)}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-380},
  year = {2000},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-380.ps.Z},
  comment = {
    This technical report contains errata for the dissertation.  Volume
    One (187 pages) is the heart of the dissertation. Volume Two (237
    pages) contains a software manual introduced with illustrated code
    fragments, plus plots of the raw data used for the experimental
    results presented in Volume One. That material is optional; I
    recommend that the interested reader begin with just Volume One.
    Volume I is available as TR2000-378.  
    Volume II is available as TR2000-379.  
  },
  abstract = {
      I tackle the problem of naming and sharing resources across
    administrative boundaries. Conventional systems manifest the hierarchy
    of typical administrative structure in the structure of their own
    mechanism.  While natural for communication that follows hierarchical
    patterns, such systems interfere with naming and sharing that cross
    administrative boundaries, and therefore cause headaches for both users
    and administrators.  I propose to organize resource naming and
    security, not around administrative domains, but around the sharing
    patterns of users.
      The dissertation is organized into four main parts.  First, I discuss
    the challenges and tradeoffs involved in naming resources and consider
    a variety of existing approaches to naming.
      Second, I consider the architectural requirements for user-centric
    sharing. I evaluate existing systems with respect to these
    requirements.
      Third, to support the sharing architecture, I develop a formal logic of
    sharing that captures the notion of restricted delegation.  Restricted
    delegation ensures that users can use the same mechanisms to share
    resources consistently, regardless of the origin of the resource, or
    with whom the user wishes to share the resource next.  A formal
    semantics gives unambiguous meaning to the logic.  I apply the
    formalism to the Simple Public Key Infrastructure and discuss how the
    formalism either supports or discourages potential extensions to such a
    system.
      Finally, I use the formalism to drive a user-centric sharing
    implementation for distributed systems.  I show how this implementation
    enables end-to-end authorization, a feature that makes heterogeneous
    distributed systems more secure and easier to audit.  Conventionally,
    gateway services that bridge administrative domains, add abstraction,
    or translate protocols typically impede the flow of authorization
    information from client to server. In contrast, end-to-end
    authorization enables us to build gateway services that preserve
    authorization information, hence we reduce the size of the trusted
    computing base and enable more effective auditing.  I demonstrate my
    implementation and show how it enables end-to-end authorization across
    various boundaries.  I measure my implementation and argue that its
    performance tracks that of similar authorization mechanisms without
    end-to-end structure.
      I conclude that my user-centric philosophy of naming and sharing
    benefits both users and administrators.
  }
}

@TechReport{Dartmouth:TR2000-381,
  author = {Guanling Chen and David Kotz},
  title = {{A Survey of Context-Aware Mobile Computing Research}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-381},
  year = {2000},
  month = {November},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-381.ps.Z},
  abstract = {
    Context-aware computing is a mobile computing paradigm in which
    applications can discover and take advantage of contextual information
    (such as user location, time of day, nearby people and devices, and
    user activity). Since it was proposed about a decade ago, many
    researchers have studied this topic and built several context-aware
    applications to demonstrate the usefulness of this new
    technology. Context-aware applications (or the system infrastructure
    to support them), however, have never been widely available to
    everyday users. In this survey of research on context-aware systems
    and applications, we looked in depth at the types of context used and
    models of context information, at systems that support collecting and
    disseminating context, and at applications that adapt to the changing
    context. Through this survey, it is clear that context-aware research
    is an old but rich area for research. The difficulties and possible
    solutions we outline serve as guidance for researchers hoping to make
    context-aware computing a reality.
  }
}

@TechReport{Dartmouth:TR2000-382,
  author = {Javed A. Aslam and Mark Montague},
  title = {{Bayes Optimal Metasearch: A Probabilistic Model for Combining the Results of Multiple Retrieval Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-382},
  year = {2000},
  month = {December},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-382.ps.Z},
  comment = {
    Preliminary version appeared in SIGIR 2000.
  },
  abstract = {
    We introduce a new, probabilistic model for combining the outputs of
    an arbitrary number of query retrieval systems.  By gathering simple
    statistics on the average performance of a given set of query
    retrieval systems, we construct a Bayes optimal mechanism for
    combining the outputs of these systems.  Our construction yields a
    metasearch strategy whose empirical performance nearly always
    exceeds the performance of any of the constituent systems.  Our
    construction is also robust in the sense that if ``good'' and
    ``bad'' systems are combined, the performance of the composite is
    still on par with, or exceeds, that of the best constituent system.
    Finally, our model and theory provide theoretical and empirical
    avenues for the improvement of this metasearch strategy.
  }
}

@TechReport{Dartmouth:TR2000-383,
  author = {Hany Farid},
  title = {{Reconstructing Ancient Egyptian Tombs}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2000-383},
  year = {2000},
  month = {December},
  URL = {http://www.cs.dartmouth.edu/reports/TR2000-383.ps.Z},
  abstract = {
     From the pyramids of Giza to the tombs of Thebes (modern Luxor),
    ancient Egypt's glorious history has produced remarkable architecture.
    Sadly, the nearly four million yearly tourists have taken a heavy toll
    on many of these ancient structures.  Of particular concern are many
    of the tombs located opposite to Luxor on the western bank of the
    Nile.  Digital reconstruction of these tombs has the potential to help
    document and preserve these important historical structures.
    Photographing and reconstruction of these tombs poses new and unique
    problems that this paper begins to address.  Techniques for removing
    image distortions, recovering 3-D shape, and correcting for lighting
    imbalances are discussed.  A complete reconstruction of the tomb of
    Sennedjem is shown.
  }
}

@TechReport{Dartmouth:TR2001-384,
  author = {Chris Bailey-Kellogg and Naren Ramakrishnan},
  title = {{Ambiguity-Directed Sampling for Qualitative Analysis of Sparse Data from Spatially-Distributed Physical Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-384},
  year = {2001},
  month = {January},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-384.ps.Z},
  abstract = {
    A number of important scientific and engineering applications, such as
    fluid dynamics simulation and aircraft design, require analysis of
    spatially-distributed data from expensive experiments and complex
    simulations.  In such data-scarce applications, it is advantageous to
    use models of given sparse data to identify promising regions for
    additional data collection.  This paper presents a principled
    mechanism for applying domain-specific knowledge to design focused
    sampling strategies.  In particular, our approach uses ambiguities
    identified in a multi-level qualitative analysis of sparse data to
    guide iterative data collection.  Two case studies demonstrate that
    this approach leads to highly effective sampling decisions that are
    also explainable in terms of problem structures and domain knowledge.
  }
}

@TechReport{Dartmouth:TR2001-385,
  author = {Xiaowen Liu and David M. Nicol and King Tan},
  title = {{Lock-free Scheduling of Logical Processes in Parallel Simulation}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-385},
  year = {2001},
  month = {January},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-385.ps.Z},
  comment = {
    A revision of this report appears on PADS 2001.
  },
  abstract = {
    With fixed lookahead information in a simulation model, the overhead
    of asynchronous conservative parallel simulation lies in the mechanism
    used for propagating time updates in order for logical processes to
    safely advance their local simulation clocks. Studies have shown that
    a good scheduling algorithm should preferentially schedule processes
    containing events on the critical path. This paper introduces a
    lock-free algorithm for scheduling logical processes in conservative
    parallel discrete-event simulation on shared-memory multiprocessor
    machines. The algorithm uses fetch\&add operations that help avoid
    inefficiencies associated with using locks. The lock-free algorithm is
    robust. Experiments show that, compared with the scheduling algorithm
    using locks, the lock-free algorithm exhibits better performance when
    the number of logical processes assigned to each processor is small or
    when the workload becomes significant. In models with large number of
    logical processes, our algorithm shows only modest increase in
    execution time due to the overhead in the algorithm for extra
    bookkeeping.
  }
}

@TechReport{Dartmouth:TR2001-386,
  author = {Robert S. Gray and David Kotz and Ronald A. Peterson and Peter Gerken and Martin Hofmann and Daria Chacon and Greg Hill and Niranjan Suri},
  title = {{Mobile-Agent versus Client/Server Performance: Scalability in an Information-Retrieval Task}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-386},
  year = {2001},
  month = {January},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-386.ps.Z},
  comment = {
    Revised version appeared in Mobile Agents 2001.
    See <a href=http://www.cs.dartmouth.edu/~dfk/papers/#gray:scalability>here</a>.
  },
  abstract = {
    Mobile agents are programs that can jump from host
    to host in the network, at times and to places of
    their own choosing. Many groups have developed
    mobile-agent software platforms, and several
    mobile-agent applications. Experiments show that
    mobile agents can, among other things, lead to
    faster applications, reduced bandwidth demands, or
    less dependence on a reliable network
    connection. There are few if any studies of the
    scalability of mobile-agent servers, particularly as
    the number of clients grows. We present some recent
    performance and scalability experiments that compare
    three mobile-agent platforms with each other and
    with a traditional client/server approach. The
    experiments show that mobile agents often outperform
    client/server solutions, but also demonstrate the
    deep interaction between environmental and
    application parameters. The three mobile-agent
    platforms have similar behavior but their absolute
    performance varies with underlying implementation
    choices. 
  }
}

@TechReport{Dartmouth:TR2001-387,
  author = {Javed A. Aslam},
  title = {{A simple bound on the expected height of a randomly built binary search tree}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-387},
  year = {2001},
  month = {Sometime},
  comment = {
    Abstract and paper lost.
  },
}

@TechReport{Dartmouth:TR2001-388,
  author = {Michael F. Ringenburg},
  title = {{Applying the Vector Radix Method to Multidimensional,  Multiprocessor, Out-of-Core Fast Fourier Transforms}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-388},
  year = {2001},
  month = {March},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-388.ps.Z},
  comment = {
    Masters Thesis.  Advisor: Tom Cormen.
  },
  abstract = {
    We describe an efficient algorithm for calculating Fast Fourier
    Transforms on matrices of arbitrarily high dimension using the
    vector-radix method when the problem size is out-of-core (i.e.,
    when the size of the data set is larger than the total available
    memory of the system).  The algorithm takes advantage of multiple
    processors when they are present, but it is also efficient on single-processor
    systems.  Our work is an extension of work done by Lauren Baptist in
    [Bapt99], which applied the vector-radix method to 2-dimensional
    out-of-core matrices.
          To determine the effectiveness of the algorithm, we present
    empirical results as well as an analysis of the I/O, communication,
    and computational complexity.  We perform the empirical tests on
    a DEC 2100 server and on a cluster of Pentium-based Linux
    workstations.  We compare our results with the traditional
    dimensional method of calculating multidimensional FFTs, and show
    that as the number of dimensions increases, the vector-radix-based
    algorithm becomes increasingly effective relative to the dimensional
    method.
          In order to calculate the complexity of the algorithm, it was
    necessary to develop a method for analyzing the interprocessor
    communication costs of the BMMC data-permutation algorithm
    (presented in [CSW98]) used by our FFT algorithms.  We present
    this analysis method and show how it was derived.
  }
}

@TechReport{Dartmouth:TR2001-389,
  author = {Thomas B. Stephens},
  title = {{Improving a Brokering System for Linking Distributed Simulations}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-389},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-389.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Linda F. Wilson.
  },
  abstract = {
    	The Agent Based Environment for Linking Simulations (ABELS) 
    is a software framework designed to provide disparate simulations 
    with dynamically updated data sources.  It allows simulations and 
    other agents to join a "cloud" of interacting producers and consumers 
    of data.  Once they have joined the cloud, they can publish services 
    to other members and use methods published by others.  This paper 
    presents the initial design of a set of matchmaking components for 
    the ABELS framework.  These components dictate how services describe 
    their abilities and requirements to ABELS.  Furthermore, they help 
    ABELS successfully match data producing services to the requests of 
    data consuming clients.
    	We begin by describing a system for a data producing service 
    to describe itself to the ABELS cloud, as well as a corresponding 
    system for a data consumer to describe its needs.  We then describe 
    in detail the three components that make up the ABELS matchmaking 
    system: the match ranker, which ranks a data producer's ability to 
    fill the request of a data consumer; the thesaurus, which helps the 
    match ranker recognize closely related terms; and the unit database, 
    which allows participants in the ABELS system to translate between 
    related data units.  We also discuss how these basic components can 
    be built upon and improved in future versions of the ABELS framework.
  }
}

@TechReport{Dartmouth:TR2001-390,
  author = {G. Ayorkor Mills-Tettey},
  title = {{Mobile Voice Over IP (MVOIP): An Application-level Protocol}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-390},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-390.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David Kotz.
  },
  abstract = {
    	Current Voice over Internet Protocol (VOIP) protocols require 
    participating hosts to have fixed IP addresses for the duration of a 
    VOIP call.  When using a wireless-enabled host, such as a tablet 
    computer on an 802.11 wireless network, it is possible for a 
    participant in a VOIP call to roam around the network, moving from 
    one subnet to another and needing to change IP addresses.  This 
    address change creates the need for mobility support in VOIP 
    applications.
    	We present the design of Mobile Voice over IP (MVOIP), an 
    application-level protocol that enables such mobility in a VOIP 
    application based on the ITU H.323 protocol stack.  An MVOIP 
    application uses hints from the surrounding network to determine that 
    it has switched subnets.  It then initiates a hand-off procedure that 
    comprises pausing its current calls, obtaining a valid IP address for 
    the current subnet, and reconnecting to the remote party with whom it 
    was in a call.  Testing the system shows that on a Windows 2000 
    platform there is a perceivable delay in the hand-off process, most 
    of which is spent in the Windows API for obtaining DHCP addresses. 
    Despite this bottleneck, MVOIP works well on a wireless network.
  }
}

@TechReport{Dartmouth:TR2001-391,
  author = {Ammar Khalid},
  title = {{A Directory Infrastructure to Support Mobile Services}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-391},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-391.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David Kotz.
  },
  abstract = {
    Traditional Voice-over-IP applications such as Microsoft NetMeeting 
    assume that the user is on a machine with a fixed IP address. If, 
    however, the user connects to the Internet, via a wireless network, 
    on a handheld device, his IP address frequently changes as he moves 
    from one subnet to another. In such a situation, we need a service 
    that can be queried for the most current IP address of a person whom 
    we wish to contact. In this project, we design and implement such a 
    directory service. The service authenticates all callers and callees, 
    is robust against most host failure, and scales to several thousand 
    registered users.
  }
}

@TechReport{Dartmouth:TR2001-392,
  author = {Arun Mathias},
  title = {{SmartReminder: A Case Study on Context-Sensitive Applications}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-392},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-392.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David Kotz.
  },
  abstract = {
    Designing context-sensitive applications is challenging. We design
    and implement SmartReminder to explore designing context-sensitive
    applications and to demonstrate how the SOLAR system can be used
    in developing such applications. SmartReminder is an application
    that reminds the user based on contextual information. Current
    appointment-reminder applications remind the user about their
    appointments at an arbitrarily specified time. For instance, they
    might remind the user ten minutes before each appointment.
    SmartReminder, on the other hand, uses contextual information,
    like location, to better estimate the appropriate reminder time
    for each appointment. It reminds the user based on where they are,
    where they need to be, and how long it will take them to get
    there. This paper presents SmartReminder as an illustration of how
    context-sensitive applications can be designed using the SOLAR
    system for dissemination of contextual information.
  }
}

@TechReport{Dartmouth:TR2001-393,
  author = {Pablo Stern},
  title = {{Measuring early usage of Dartmouth's wireless network}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-393},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-393.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David Kotz.
  },
  abstract = {
    In Spring 2001, Dartmouth College installed a campus-wide 802.11b 
    wireless network. To understand how that network is used, we examined 
    the usage characteristics of the network over a five-week period. We 
    monitored access points to determine user behavior, and user and 
    network traffic characteristics. Because our study coincided with the 
    deployment of the access points, our analysis captures the growth of 
    a wireless network. The results of this study help understand the 
    behavior of mobile users and provide a reference to network engineers 
    wishing to deploy and expand similar wireless networks.
  }
}

@TechReport{Dartmouth:TR2001-394,
  author = {David D. Latham},
  title = {{An Empirical Study of Training and Testing Error in Boosting}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-394},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-394.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Jay Aslam.
  },
  abstract = {
    Bounds have been proven for both training and testing error for the boosting
    algorithm AdaBoost, but in practice neither seem to produce a particularly
    tight bound.  In this paper we share some observations of these bounds from
    empirical results, and then explore some properties of the algorithm with an
    eye towards finding an improved bound for the performance of AdaBoost.
    Based on our empirical evidence, the error of a hypothesis which labels
    examples probabilistically based upon the confidence of the vote of the weak
    hypotheses forms a tighter bound for the training error.
  }
}

@TechReport{Dartmouth:TR2001-395,
  author = {Tiffany M. Wong},
  title = {{An Implementation of Object-Oriented Program Transformation for Thought-Guided Debugging	}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-395},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-395.ps.Z},
  comment = {
    Senior Honors Thesis. Advisor: Tom Cormen
  },
  abstract = {
    This paper presents our design and implementation of program transformation for
    C++ that will be used in the context of a thought-guided debugging system. The
    program uses a lexical analyzer written in Flex and a grammar written in Bison
    that work in conjunction to scan the inputted C++ code for function definitions
    and class definitions. The code is then transformed to produce trace
    information for each defined function, while the original functionality of the
    code is left untouched. We also implement two additional data structures that
    are used for information storage during the course of the program.
  }
}

@TechReport{Dartmouth:TR2001-396,
  author = {Tiffany M. Wong},
  title = {{Implementing a Database Information System for an Electronic Baseball Scorecard	}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-396},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-396.ps.Z},
  comment = {
    Senior Honors Thesis. Advisor: Tom Cormen
  },
  abstract = {
    We present our design and implementation of a database system of information
    storage and retrieval for an electronic baseball scorecard. The program uses
    the relational MySQL database to hold information and a Tcl API to handle
    interactions between the database and the user interface code. This paper
    discusses the inner workings of how information storage was broken down inside
    the database, how queries were internally constructed in accordance with the
    user's input, and how statistics for players and teams were calculated and
    returned to the user. Finally, we discuss some limitations attached to our
    current implementation of the program and propose improvements that can be made
    in future versions.
  }
}

@TechReport{Dartmouth:TR2001-397,
  author = {Guanling Chen and David Kotz},
  title = {{Supporting Adaptive Ubiquitous Applications with the SOLAR System}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-397},
  year = {2001},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-397.ps.Z},
  abstract = {
    As we embed more computers into our daily environment, ubiquitous
    computing promises to make them less noticeable and help to prevent
    information overload. We see, however, few ubiquitous applications
    that are able to adapt to the dynamics of user, physical, and
    computational context. We believe that there are two challenges
    causing this lack of ubiquitous applications: there is no flexible and
    scalable way to support information collection and dissemination in a
    ubiquitous and mobile environment, and there is no general approach to
    building adaptive applications given heterogeneous contextual
    information. We propose a system infrastructure, Solar, to meet these
    challenges. Solar uses a subscription-based operator graph abstraction
    and allows dynamic composition of stackable operators to manage
    ubiquitous information sources. After developing a set of diverse
    adaptive applications, we expect to identify fundamental techniques
    for context-aware adaptation. Our expectation is that Solar's
    end-to-end support for information collection, dissemination, and
    utilization will make it easy to build adaptive applications for a
    ubiquitous mobile environment with many users and devices.
  }
}

@TechReport{Dartmouth:TR2001-398,
  author = {David Marmaros},
  title = {{A System for Audio Personalization with Applications on Wireless Devices}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-398},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-398.pdf},
  comment = {
    Senior Honors Thesis. Advisors: David Kotz and Daniela Rus.
  },
  abstract = {
    We present and analyze a system for dynamically tailoring discrete audio content for numerous users based on aggregate data and intuitive feedback mechanisms.  The framework for this system utilizes a flexible client-server architecture to facilitate audio dissemination, with particular attention to distribution over wireless networks.   We discuss the requirements and specifications of such a system.  We further analyze the algorithms and protocols required for its operation.  Finally, we outline and provide data from a demonstration of this application.
  }
}

@TechReport{Dartmouth:TR2001-399,
  author = {Shan Jiang},
  title = {{WebALPS Implementation and Performance Analysis: Using Trusted Co-servers to Enhance Privacy and Security of Web Interactions}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-399},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-399.ps.Z},
  comment = {
    Master's thesis.
  },
  abstract = {
         The client-server model of the Web poses a fundamental trust issue:
    clients are forced to trust in secrecy and correctness of computation
    occurring at a remote server of unknown credibility.  The current solution
    for this problem is to use a PKI (Public Key Infrastructure) system and
    SSL (Secure Sockets Layer) digital certificates to prove the claimed
    identity of a server and establish an authenticated, encrypted channel
    between the client and this server.  However, this approach does not
    address the security risks posed by potential malicious server
    operators or any third parties who may penetrate the server sites.
         The WebALPS (Web Applications with Lots of Privacy and Security)
    approach is proposed to address these weaknesses by moving sensitive
    computations at server side into trusted co-servers running inside
    high-assurance secure coprocessors.
         In this report, we examine the foundations of the credibility of
    WebALPS co-servers. Then we will describe our work of designing and
    building a prototype WebALPS co-server, which is integrated into the
    widely-deployed, commercial-grade Apache server.  We will also present
    the performance test results of our system which support the argument
    that WebALPS approach provides a systematic and practical way to address the
    remote trust issue.
  }
}

@TechReport{Dartmouth:TR2001-400,
  author = {Alex Iliev},
  title = {{An Armored Data Vault}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-400},
  year = {2001},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-400.pdf},
  comment = {
    Senior Honors Thesis. 
    Advisor: Sean Smith.
  },
  abstract = {
    We consider the problem of secure long-term archiving of
    network traffic, an instance of the problem of storing data
    securely. We approach the problem using secure hardware, which enables
    the enforcement of flexible access policy. The policy cannot be
    circumvented by anyone, even insiders, and so we are assured that
    access to the data is as originally intended. The policy can be
    expressed as any feasible computation, as it will be checked inside
    the secure hardware without possibility of interference. We discuss
    our design of a device to perform such network data archiving and have
    implemented a prototpe device. We discuss other possible application
    areas of the design.
  }
}

@TechReport{Dartmouth:TR2001-401,
  author = {Sean W. Smith},
  title = {{Outbound Authentication for Programmable Secure Coprocessors}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-401},
  year = {2001},
  month = {March},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-401.ps.Z},
  abstract = {
       A programmable secure coprocessor platform can help solve many
    security problems in distributed computing.  These solutions usually
    require that coprocessor applications be able to participate as
    full-fledged parties in distributed cryptographic protocols.  Thus, to
    fully enable these solutions, a generic platform must not only provide
    programmability, maintenance, and configuration in the hostile
    field---it must also provide outbound authentication for the
    entities that result.  A particular application on a particular
    untampered device must be able to prove who it is to a party on the
    other side of the Internet.
       To be effective, a secure outbound authentication service must closely
    mesh with the overall security architecture.  Our initial architecture
    only sketched a rough design for this service, and did not complete
    it.  This paper presents our research and development experience in
    refining and implementing this design, to provide PKI-based outbound
    authentication for the IBM 4758 Model 2 secure coprocessor platform.
  }
}

@TechReport{Dartmouth:TR2001-402,
  author = {Jeremy T. Fineman},
  title = {{Optimizing the Dimensional Method for Performing Multidimensional, Multiprocessor, Out-of-Core FFTs}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-402},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-402.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Tom Cormen.
  },
  abstract = {
        We present an improved version of the Dimensional Method for computing
    multidimensional Fast Fourier Transforms (FFTs) on a multiprocessor
    system when the data consist of too many records to fit into
    memory. Data are spread across parallel disks and processed in
    sections. We use the Parallel Disk Model for analysis.
        The simple Dimensional Method performs the 1-dimensional FFTs for
    each dimension in term. Between each dimension, an out-of-core
    permutation is used to rearrange the data to contiguous locations.
    The improved Dimensional Method processes multiple dimensions at a
    time.
        We show that determining an optimal sequence and groupings of
    dimensions is NP-complete. We then analyze the effects of two
    modifications to the Dimensional Method independently: processing
    multiple dimensions at one time, and processing single dimensions in a
    different order.
        Finally, we show a lower bound on the I/O complexity of the
    Dimensional Method and present an algorithm that is approximately
    asymptotically optimal.
  }
}

@TechReport{Dartmouth:TR2001-403,
  author = {Aidan S. Marcuss},
  title = {{EcomRISK.org : A site to classify and organize the risks of  performing business on the Internet}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-403},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-403.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Fillia Makedon.
  },
  abstract = {
    As the use of the Internet and other computer networks to transact 
    business grows, there is an ever increasing need for those taking 
    part in those transactions to understand the risks of doing so. While 
    there are many web sites that have created valuable databases of 
    specific vulnerabilities for certain types of hardware and software, 
    there is a lack of focus on attempting to analyze the interaction of 
    businesses, their systems, computer networks, and their customers and 
    the risks that are created by either intended or unattended 
    interactions. EcomRISK.org is a web site that presents a clear 
    taxonomy to classify these risks and provides other features to aid 
    in the general discussion of e-commerce risk. The site, and the 
    taxonomy at the center of it, creates a database of these incidents 
    so they can be clearly searched. This paper discusses the creation of 
    EcomRISK.org, from vision to birth.
  }
}

@TechReport{Dartmouth:TR2001-404,
  author = {Eric Kidd},
  title = {{Efficient Compression of Generic Function Dispatch Tables}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-404},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-404.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Chris Hawblitzel.
  },
  abstract = {
      A generic function is similar to an overloaded operator, but provides a way
    to select an appropriate behavior at run-time instead of compile-time.
    Dujardin and colleagues have proposed an algorithm for building and
    compressing generic function dispatch tables.
       We present several modifications to their algorithm, including an
    improvement to Pseudo-Closest-Poles and two new algorithms for compressing
    pole tables.  The two new compression algorithms are simple and fast, and
    one produces smaller output than the original.
  }
}

@TechReport{Dartmouth:TR2001-405,
  author = {Mehmet Iyigun},
  title = {{DaSSFNet: An Extension to DaSSF for High-Performance Network Modeling}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-405},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-405.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David M. Nicol
  },
  abstract = {
    Scalable Simulation Framework (SSF) is a discrete-event simulation 
    framework providing a unified programming interface geared towards 
    network simulation. Dartmouth SSF (DaSSF) is a C++ implementation of 
    SSF, designed for simulating very large-scale multi-protocol 
    communication networks. As of the latest release, DaSSF lacks many 
    features present in SSF and this prevents it from achieving 
    mainstream use. To alleviate this shortcoming we designed and 
    implemented DaSSFNet which extends DaSSF to the levels of 
    functionality found in SSF. In this paper, we show that DaSSFNet and 
    SSFNet are identical in operation given the same input. We also show 
    that DaSSFNet is about twice as fast and has one third the memory 
    consumption of SSFNet when simulating identical networks. Therefore, 
    we argue, that the DaSSF simulation package with DaSSFNet now offers 
    a viable alternative to SSF in high-performance network simulation.
  }
}

@TechReport{Dartmouth:TR2001-406,
  author = {Jeremy I. Robin},
  title = {{Fastab: Solving the Pitch to Notation Problem}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-406},
  year = {2001},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-406.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Scot Drysdale
  },
  abstract = {
    I have always been frustrated with the length of time necessary to 
    notate a piece of music. Computers have simplified so many other 
    aspects of our lives, it seems that they should be able to simplify 
    this task as well.  In fact, there are already two distinct ways that 
    engineers have attempted to attack this problem.  The first analyzes 
    the waveform generated by microphone input and relies on Fourier 
    Analysis and other similar methods.  The other examines the analog 
    signal generated by a electric guitar-like pickup placed beneath the 
    strings. The method used by Fastab relies much less on the musical 
    properties of an instrument.  Instead, Fastab records where and when 
    the fingers and pick contact the instrument using digital electronics 
    and microprocessor technology.  Fastab provides a solution to the 
    pitch to notation problem which is cheaper and more accurate than any 
    other device available today.
  }
}

@TechReport{Dartmouth:TR2001-407,
  author = {Michael G. Khankin},
  title = {{TCP/IP Implementation within the Dartmouth Scalable Simulation Framework}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-407},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-407.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David M. Nicol
  },
  abstract = {
    	This paper discusses TCP/IP networking, and in particular, the DaSSF
    implementation of TCP/IP.  The paper reviews the protocols, outlines the
    implementation design, and demonstrates some tests.  In addition, some
    performance and memory usage analysis is performed.
    	We find DaSSF TCP/IP to be a viable option to the existing SSF.  DaSSF
    TCP/IP is faster and uses less memory so we can simulate larger, more
    complex, models.
  }
}

@TechReport{Dartmouth:TR2001-408,
  author = {Jonathan L. Bredin},
  title = {{Market-based Control of Mobile-agent Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-408},
  year = {2001},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-408.ps.Z},
  comment = {
    A Ph.D thesis from the Department of Computer Science, Dartmouth College.
  },
  abstract = {
    Modern distributed systems scatter sensors, storage, and computation
    throughout the environment.
    Ideally these devices communicate and share resources, but there
    is seldom motivation for a device's owner to yield control to another user.
    We establish markets for computational resources
    to motivate principals to share resources with arbitrary users, to enforce
    priority in distributed systems, to provide flexible and rational limitations
    on the potential of an application, and to provide a lightweight structure
    to balance the workload over time and between devices.
    As proof of concept, we implement a structure software agents
    can use to discover and negotiate access to networked resources.
    The structure separates discovery, authentication, and consumption
    enforcement as separate orthogonal issues to give system
    designers flexibility.
    	Mobile agents represent informational and computational flow.
    We develop mechanisms that distributively allocate computation among
    mobile agents in two settings.
    The first models a situation where users collectively own networked
    computing resources and require priority enforcement.
    We extend the allocation mechanism to allow
    resource reservation to mitigate utility volatility.
    The second, more general model relaxes the ownership assumption.
    We apply our computational market to an open setting where a principal's
    chief concern is revenue maximization.
    	Our simulations compare the performance of market-based allocation
    policies to traditional policies and relate the cost of ownership and
    consumption separation.
    We observe that our markets effectively prioritize applications'
    performance, can operate under uncertainty and network delay, provide
    metrics to balance network load, and allow measurement of
    market-participation risk versus reservation-based computation.
    	In addition to allocation problems, we investigate resource selection
    to optimize execution time.
    The problem is NP-complete if the costs and latencies are constant.
    Both metrics' dependence on the chosen set complicates matters.
    We study how a greedy approach, a novel heuristic, and a
    shortest-constrained-path strategy perform in mobile-agent applications.
    	Market-based computational-resource allocation fertilizes
    applications where previously there was a dearth of motive for or means
    of cooperation.
    The rationale behind mobile-agent performance optimization is also useful
    for resource allocation in general distributed systems where an application
    has a sequence of dependent tasks or when data collection is expensive.
  }
}

@TechReport{Dartmouth:TR2001-409,
  author = {Yougu Yuan and Eileen Zishuang Ye and Sean W. Smith},
  title = {{Web Spoofing 2001}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-409},
  year = {2001},
  month = {July},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-409.ps.Z},
  abstract = {
      The Web is currently the pre-eminent medium for electronic
    service delivery to remote users. As a consequence,
    authentication of servers is more important than ever. Even
    sophisticated users base their decision whether or not to trust a
    site on browser cues---such as location bar information, SSL
    icons, SSL warnings, certificate information, response time, etc.
    
      In their seminal work on web spoofing, Felten et al showed how a
    malicious server could forge some of these cues---but using
    approaches that are no longer reproducible.  However, subsequent
    evolution of Web tools has not only patched security holes---it
    has also added new technology to make pages more interactive and
    vivid. In this paper, we explore the feasibility of web spoofing
    using this new technology---and we show how, in many cases, every
    one of the above cues can be forged.
    
      In particular, we show how a malicious server can forge all the
    SSL information a client sees---thus providing a cautionary tale
    about the security of one of the most common applications of PKI.
    
      We stress that these techniques have been implemented, and are
    available for public demonstration. 
  }
}

@TechReport{Dartmouth:TR2001-410,
  author = {Shan Jiang and Sean Smith and Kazuhiro Minami},
  title = {{Securing Web Servers against Insider Attack}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-410},
  year = {2001},
  month = {July},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-410.ps.Z},
  abstract = {
      Too often, ``security of Web transactions'' reduces to ``encryption of
    the channel''---and neglects to address what happens at the server on
    the other end.  This oversight forces clients to trust the good
    intentions and competence of the server operator---but gives clients
    no basis for that trust.  Furthermore, despite academic and industrial
    research in secure coprocessing, many in the computer science
    community still regard ``secure hardware'' as a synonym for
    ``cryptographic accelerator.'  This oversight neglects the real
    potential of COTS secure coprocessing technology to establish trusted
    islands of computation in hostile environments---such as at web
    servers with risk of insider attack.
    
      In this paper, we apply secure coprocessing and cryptography to solve
    this real problem in Web technology.  We present a vision: using
    secure coprocessors to establish trusted co-servers at Web servers and
    moving sensitive computations inside these co-servers.  We present a
    prototype implementation of this vision that scales to realistic
    workloads.  Finally, we validate this approach by building a simple
    E-voting application on top of our prototype.
    
      From our experience, we conclude that this approach provides a
    practical and effective way to enhance the security of Web servers
    against insider attack.
  }
}

@TechReport{Dartmouth:TR2001-411,
  author = {Arne Grimstrup and Robert S. Gray and David Kotz and Thomas Cowin and Greg Hill and Niranjan Suri and Daria Chacon and Martin Hofmann},
  title = {{Write Once, Move Anywhere: Toward Dynamic Interoperability of Mobile Agent Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-411},
  year = {2001},
  month = {July},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-411.ps.Z},
  comment = {
    Revised July 25, 2001.
  },
  abstract = {
    Mobile agents are an increasingly popular paradigm,
    and in recent years there has been a proliferation
    of mobile-agent systems. These systems are, however,
    largely incompatible with each other. In particular,
    agents cannot migrate to a host that runs a
    different mobile-agent system. Prior approaches to
    interoperability have tried to force agents to use a
    common API, and so far none have succeeded. Our
    goal, summarized in the catch phrase ``Write
    Once, Move Anywhere,'' led to our efforts to develop
    mechanisms that support dynamic runtime
    interoperability of mobile-agent systems. This paper
    describes the Grid Mobile-Agent System,
    which allows agents to migrate to different
    mobile-agent systems.
  }
}

@TechReport{Dartmouth:TR2001-412,
  author = {Hany Farid},
  title = {{Detecting Steganographic Messages in Digital Images}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-412},
  year = {2001},
  month = {September},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-412.ps.Z},
  abstract = {
    Techniques and applications for information hiding have
    become increasingly more sophisticated and widespread. With
    high-resolution digital images as carriers, detecting the presence of
    hidden messages has also become considerably more difficult. It is
    sometimes possible, nevertheless, to detect (but not necessarily
    decipher) the presence of embedded messages. The basic approach taken
    here works by finding predictable higher-order statistics of
    ``natural'' images within a multi-scale decomposition, and then
    showing that embedded messages alter these statistics.
  }
}

@TechReport{Dartmouth:TR2001-413,
  author = {Senthil Periaswamy and Hany Farid},
  title = {{Differential Elastic Image Registration}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2001-413},
  year = {2001},
  month = {September},
  URL = {http://www.cs.dartmouth.edu/reports/TR2001-413.ps.Z},
  abstract = {
    We have applied techniques from differential motion
    estimation to the problem of automatic elastic registration of medical
    images. This method models the mapping between images as a locally
    affine but globally smooth warp. The mapping also explicitly accounts
    for variations in image intensities. This approach is simple and
    highly effective across a broad range of medical images. We show the
    efficacy of this approach on several synthetic and clinical images.
  }
}

@TechReport{Dartmouth:TR2002-414,
  author = {Valentino Crespi and George Cybenko and Massimo Santini and Daniela Rus},
  title = {{Decentralized Control for Coordinated flow of Multi-Agent Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-414},
  year = {2002},
  month = {January},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-414.ps.Z},
  abstract = {
    This paper describes a distributed algorithm for coordinating the flow
    of a mass of vehicles approaching a highway exit or a tollbooth. We
    provide the problem formulation, a general methodology for distributed
    control and an instantiation of this methodology to the coordinated
    flow problem. We analyze our algorithm and provide experimental data.
  }
}

@TechReport{Dartmouth:TR2002-415,
  author = {David Kotz and Robert S. Gray and Daniela Rus},
  title = {{Future Directions for Mobile-Agent Research}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-415},
  year = {2002},
  month = {January},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-415.ps.Z},
  abstract = {
    During a discussion in September 2000 the authors
    examined the future of research on mobile agents and
    mobile code. (A mobile agent is a running program
    that can move from host to host in network at times
    and to places of its own choosing.) In this paper we
    summarize and reflect on that discussion. It became
    clear that the field should shift its emphasis
    toward mobile code, in all its forms, rather than to
    continue its narrow focus on mobile
    agents. Furthermore, we encourage the development of
    modular components, so that application designers
    may take advantage of code mobility without needing
    to rewrite their application to fit in a monolithic
    mobile-agent system. There are many potential
    applications that may productively use mobile code,
    but there is no ``killer application'' for mobile
    agents. Finally, we note that although security is
    an important and challenging problem, there are many
    applications and environments with security
    requirements well within the capability of existing
    mobile-code and mobile-agent frameworks. 
  }
}

@TechReport{Dartmouth:TR2002-416,
  author = {John C. Marchesini and Sean W. Smith},
  title = {{Virtual Hierarchies - An Architecture for Building and Maintaining Efficient and Resilient Trust Chains.}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-416},
  year = {2002},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-416.ps.Z},
  abstract = {
    In Public Key Infrastructure (PKI), the simple, monopolistic CA model
    works fine until we consider the real world. Then, issues such as
    scalability and mutually suspicious organizations create the need for
    a multiplicity of CAs, which immediately introduces the problem of how
    to organize them to balance resilience to compromise against
    efficiency of path discovery.
      However, security has given us tools such as secure coprocessing,
    secret splitting, secret sharing, and threshold cryptography for
    securely carrying out computations among multiple trust domains;
    distributed computing has given us peer-to-peer networking, for
    creating self-organizing distributed systems.
      In this paper, we use these latter tools to address the former
    problem by overlaying a virtual hierarchy on a mesh architecture of
    peer CAs, and achieving both resilience and efficiency.
  }
}

@TechReport{Dartmouth:TR2002-417,
  author = {Eileen Ye and Yougu Yuan and Sean Smith},
  title = {{Web Spoofing Revisited: SSL and Beyond}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-417},
  year = {2002},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-417.ps.Z},
  comment = {
    This TR supercedes TR2001-409.
  },
  abstract = {
       Can users believe what their browsers tell them?  Even sophisticated
    Web users decide whether or not to trust a server based on browser
    cues such as location bar information, SSL icons, SSL warnings,
    certificate information, and response time.  In their seminal work on
    Web spoofing, Felten et al showed how, in 1996, a
    malicious server could forge some of these cues.  However, this work
    used genuine SSL sessions, and Web technology has evolved much since
    1996.
       The Web has since become the pre-eminent medium for electronic service
    delivery to remote users, and the security of many commerce,
    government, and academic network applications critically rests on the
    assumption that users can authenticate the servers with which they
    interact.  This situation raises the question: is the browser-user
    communication model today secure enough to warrant this assumption?
       In this paper, we answer this question by systematically showing how a
    malicious server can forge every one of the above cues.  Our work
    extends the prior results by examining contemporary browsers, and by
    forging all of the SSL information a client sees, including the very
    existence of an SSL session (thus providing a cautionary tale about
    the security of one of the most common applications of PKI).  We have
    made these techniques available for public demonstration, because
    anything less than working code would not convincingly answer the
    question.  We also discuss implications and potential countermeasures,
    both short-term and long-term.
  }
}

@TechReport{Dartmouth:TR2002-418,
  author = {Eileen Ye and Sean Smith},
  title = {{Trusted Paths for Browsers: An Open-Source Solution to Web Spoofing}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-418},
  year = {2002},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-418.ps.Z},
  abstract = {
       The security of the vast majority of ``secure'' Web services rests on
    SSL server PKI.  However, this PKI doesn't work if the the adversary
    can trick the browser into appearing to tell the user the wrong thing
    about the certificates and cryptography.  The seminal web spoofing
    work of Felten et al demonstrated the potential, in 1996, for
    malicious servers to impersonate honest servers.  Our recent follow-up
    work explicitly shows how malicious servers can still do this---and
    can also forge the existence of an SSL session and the contents of the
    alleged server certificate.
        This paper reports the results of our work to systematically defend
    against Web spoofing, by creating a trusted path from the browser to
    the user.  Starting with the Mozilla source, we have implemented
    techniques that protect a wide variety of browser-user communications,
    that require little participation by the user and minimal disruption
    of the displayed server content.  We have prepared shell scripts that
    install these modifications on the Mozilla source, to enable others to
    replicate this work.
        In on-going work, we are cleaning up and fine-tuning our code.  In
    future work, we hope to examine more deeply the role of user
    interfaces in enabling users to make effective trust judgments.
  }
}

@TechReport{Dartmouth:TR2002-419,
  author = {Dennis M. Healy and Daniel N. Rockmore and Peter J. Kostelec and Sean S. B. Moore},
  title = {{FFTs for the 2-Sphere - Improvements and Variations}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-419},
  year = {2002},
  month = {March},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-419.ps.Z},
  comment = {
      Preliminary versions of some of these results have appeared in the
    Dartmouth College Department of Computer Science Technical Report
    PCS-TR94-222 and ``An FFT for the 2-sphere and Applications'',
    Proc. of ICASSP-96, Volume 3, pp. 1323--1326.
  },
  abstract = {
       Earlier work by Driscoll and Healy has produced an efficient
    algorithm for computing the Fourier transform of band-limited
    functions on the 2-sphere. In this paper we present a reformulation
    and variation of the original algorithm which results in a greatly
    improved inverse transform, and consequent improved convolution
    algorithm for such functions. All require at most $O(N\log^2 N)$
    operations where $N$ is the number of sample points. We also address
    implementation considerations and give heuristics for allowing
    reliable and computationally efficient floating point implementations
    of slightly modified algorithms.
       These claims are supported by extensive numerical experiments from
    our implementation in C on DEC, HP, SGI and Linux Pentium
    platforms. These results indicate that variations of the algorithm
    are both reliable and efficient for a large range of useful problem
    sizes.  Performance appears to be architecture-dependent.  The paper
    concludes with a brief discussion of a few potential applications.
  }
}

@TechReport{Dartmouth:TR2002-420,
  author = {Guanling Chen and David Kotz},
  title = {{Context Aggregation and Dissemination in Ubiquitous Computing Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-420},
  year = {2002},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-420.ps.Z},
  comment = {
    To appear in WMCSA 2002.
  },
  abstract = {
      Many ``ubiquitous computing'' applications need a constant flow of
    information about their environment to be able to adapt to their
    changing context. To support these ``context-aware'' applications we
    propose a graph-based abstraction for collecting, aggregating, and
    disseminating context information. The abstraction models context
    information as events, produced by sources and flowing through a
    directed acyclic graph of event-processing operators and delivered to
    subscribing applications. Applications describe their desired event
    stream as a tree of operators that aggregate low-level context
    information published by existing sources into the high-level context
    information needed by the application. The operator graph is thus the
    dynamic combination of all applications' subscription trees.
    
      In this paper, we motivate and describe our graph abstraction, and
    discuss a variety of critical design issues. We also sketch our Solar
    system, an implementation that represents one point in the design
    space for our graph abstraction.
  }
}

@TechReport{Dartmouth:TR2002-421,
  author = {Guanling Chen and David Kotz},
  title = {{Solar: A pervasive-computing infrastructure for context-aware mobile applications}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-421},
  year = {2002},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-421.ps.Z},
  abstract = {
    Emerging pervasive computing technologies transform the way we live
    and work by embedding computation in our surrounding environment.  To
    avoid increasing complexity, and allow the user to concentrate on her
    tasks, applications must automatically adapt to their changing
    \emph{context}, the physical and computational environment in which
    they run.  To support these ``context-aware'' applications we propose
    a graph-based abstraction for collecting, aggregating, and
    disseminating context information.  The abstraction models context
    information as \emph{events}, which are produced by \emph{sources},
    flow through a directed acyclic graph of event-processing
    \emph{operators}, and are delivered to subscribing applications.
    Applications describe their desired event stream as a tree of
    operators that aggregate low-level context information published by
    existing sources into the high-level context information needed by the
    application.  The \emph{operator graph\/} is thus the dynamic
    combination of all applications' subscription trees.  In this paper,
    we motivate our graph abstraction by discussing several applications
    under development, sketch the architecture of our system (``Solar'')
    that implements our abstraction, report some early experimental
    results from the prototype, and outline issues for future research.
  }
}

@TechReport{Dartmouth:TR2002-422,
  author = {Kazuhiro Minami and David Kotz},
  title = {{Controlling access to pervasive information in the ``Solar'' system}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-422},
  year = {2002},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-422.ps.Z},
  abstract = {
      Pervasive-computing infrastructures necessarily collect a lot of
    context information to disseminate to their context-aware
    applications.  Due to the personal or proprietary nature of much of
    this context information, however, the infrastructure must limit
    access to context information to authorized persons.  In this paper we
    propose a new access-control mechanism for event-based
    context-distribution infrastructures.  The core of our approach is
    based on a conservative information-flow model of access control, but
    users may express discretionary relaxation of the resulting
    access-control list (ACL) by specifying relaxation functions.
    This combination of automatic ACL derivation and user-specified ACL
    relaxation allows access control to be determined and enforced in a
    decentralized, distributed system with no central administrator or
    central policy maker.  It also allows users to express their personal
    balance between functionality and privacy.  Finally, our
    infrastructure allows access-control policies to depend on
    context-sensitive roles, allowing great flexibility.  
    
      We describe our approach in terms of a specific context-dissemination
    framework, the Solar system, although the same principles would apply
    to systems with similar properties.
  }
}

@TechReport{Dartmouth:TR2002-423,
  author = {David Kotz and Kobby Essien},
  title = {{Characterizing Usage of a Campus-wide Wireless Network}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-423},
  year = {2002},
  month = {March},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-423.ps.Z},
  comment = {
    A major revision of this paper appeared in Mobicom 2002.
    The Mobicom paper contained two erroneous figures, however;
    another report, TR2002-432, is the final corrected version. 
  },
  abstract = {
      Wireless local-area networks (WLANs) are increasingly common, but
    little is known about how they are used.  A clear understanding of
    usage patterns in real WLANs is critical information to those who
    develop, deploy, and manage WLAN technology, as well as those who
    develop systems and application software for wireless networks.  This
    paper presents results from the largest and most comprehensive trace
    of network activity in a large, production wireless LAN.  For eleven
    weeks we traced the activity of nearly two thousand users drawn from a
    general campus population, using a campus-wide network of 476 access
    points spread over 161 buildings.  Our study expands on those done by
    Tang and Baker, with a significantly larger and broader population.
    
      We found that residential traffic dominated all other traffic,
    particularly in residences populated by newer students; students are
    increasingly choosing a wireless laptop as their primary computer.
    Although web protocols were the single largest component of traffic
    volume, network backup and file sharing contributed an unexpectedly
    large amount to the traffic.  Although there was some roaming within a
    network session, we were surprised by the number of situations in
    which cards roamed excessively, unable to settle on one access point.
    Cross-subnet roams were an especial problem, because they broke IP
    connections, indicating the need for solutions that avoid or
    accommodate such roams.
  }
}

@TechReport{Dartmouth:TR2002-424,
  author = {Mark H. Montague},
  title = {{Metasearch: Data Fusion for Document Retrieval}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-424},
  year = {2002},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-424.ps.Z},
  comment = {
    Ph.D dissertation.
  },
  abstract = {
        The metasearch problem is to optimally merge the ranked lists
    output by an arbitrary number of search systems into one ranked list.
    In this work:
        (1) We show that metasearch improves upon not just the raw performance
    of the input search engines, but also upon the consistency of the
    input search engines from query to query.
        (2) We experimentally prove that simply weighting input systems by
    their average performance can dramatically improve fusion results.
        (3) We show that score normalization is an important component of a
    metasearch engine, and that dependence upon statistical outliers
    appears to be the problem with the standard technique.
        (4) We propose a Bayesian model for metasearch that outperforms the
    best input system on average and has performance competetive with
    standard techniques.
        (5) We introduce the use of Social Choice Theory to the metasearch
    problem, modeling metasearch as a democratic election.  We adapt a
    positional voting algorithm, the Borda Count, to create a metasearch
    algorithm, acheiving reasonable performance.
        (6) We propose a metasearch model adapted from a majoritarian voting
    procedure, the Condorcet algorithm.  The resulting algorithm is the
    best performing algorithm in a number of situations.
        (7) We propose three upper bounds for the problem, each bounding a
    different class of algorithms.
        We present experimental results for each algorithm using two types of
    experiments on each of four data sets.
  }
}

@TechReport{Dartmouth:TR2002-425,
  author = {Marco A. Barreno},
  title = {{The Future of Cryptography Under Quantum Computers}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-425},
  year = {2002},
  month = {July},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-425.ps.Z},
  comment = {
    This paper was written as a senior honors thesis with advisor Sean
    W. Smith.
  },
  abstract = {
      Cryptography is an ancient art that has passed through many
    paradigms, from simple letter substitutions to polyalphabetic
    substitutions to rotor machines to digital encryption to public-key
    cryptosystems.  With the possible advent of quantum computers and the
    strange behaviors they exhibit, a new paradigm shift in cryptography
    may be on the horizon.  Quantum computers could hold the potential to
    render most modern encryption useless against a quantum-enabled
    adversary.  The aim of this thesis is to characterize this convergence
    of cryptography and quantum computation.
      We provide definitions for cryptographic primitives that frame them
    in general terms with respect to complexity.  We explore the various
    possible relationships between BQP, the primary quantum complexity
    class, and more familiar classes, and we analyze the possible
    implications for cryptography.
  }
}

@TechReport{Dartmouth:TR2002-426,
  author = {Christopher P. Masone},
  title = {{Role Definition Language (RDL): A Language to Describe  Context-Aware Roles}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-426},
  year = {2002},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-426.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David Kotz.
  },
  abstract = {
    	As wireless networks become more prevalent, a widening array 
    of computational resources becomes available to the mobile user. 
    Since not all users should have unrestricted access to these 
    resources, a method of access control must be devised.  In a 
    context-aware environment, context information can be used to 
    supplement more conventional password-based access control systems. 
    We believe the best way to achieve this is through the use of 
    Context-Aware Role-Based Access Control, a model in which permissions 
    are assigned to entities called roles, each principal is a member of 
    one or more roles, and a role's membership is determined using 
    context information.  We designed and implemented RDL 
    (Role-Definition Language), a simple, expressive and somewhat 
    extensible programming language to facilitate the description of 
    roles in terms of context information.
  }
}

@TechReport{Dartmouth:TR2002-427,
  author = {A. Abram White},
  title = {{Performance and Interoperability In Solar}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-427},
  year = {2002},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-427.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: David Kotz.
    See also TR2002-429.
  },
  abstract = {
    Ubiquitous computing promises to integrate computers into our physical
    environment, surrounding us with applications that are able to adapt
    to our dynamics.  Solar is a software infrastructure designed to
    deliver contextual information to these applications.  To serve the
    large number and wide variety of context-aware devices envisioned by
    ubiquitous computing, Solar must exhibit both high performance and the
    ability to interoperate with many computing platforms.  We created a
    testing framework to measure the performance of distributed systems
    such as Solar, as well as a pluggable data-transfer mechanism to
    support the dissemination of information to heterogeneous
    applications.  This paper explores the testing framework developed,
    analyzes its findings concerning the performance of the current Solar
    prototype, presents several optimizations to Solar and their effects,
    and finally discusses the design of the pluggable data-transfer
    mechanism.
  }
}

@TechReport{Dartmouth:TR2002-428,
  author = {Sebastien M. Lahaie},
  title = {{Information-theoretic Bounds on the Training and Testing Error of Boosting}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-428},
  year = {2002},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-428.ps.Z},
  abstract = {
    Boosting is a means of using weak learners as subroutines to produce a
    strong learner with markedly better accuracy. Recent results showing
    the connection between logistic regression and boosting provide the
    foundation for an information-theoretic analysis of boosting. We
    describe the analogy between boosting and gambling, which allows us to
    derive a new upper bound on training error. This upper bound
    explicitly describes the effect of noisy data on training error. We
    also use information-theoretic techniques to derive an alternative upper-bound
    on testing error which is independent of the size of the weak-learner
    space.
  }
}

@TechReport{Dartmouth:TR2002-429,
  author = {A. Abram White},
  title = {{XSLT and XQuery as Operator Languages}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-429},
  year = {2002},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-429.ps.Z},
  comment = {
    See also TR2002-427.
  },
  abstract = {
    Ubiquitous computing promises to integrate computers into our physical
    environment, surrounding us with applications that are able to adapt
    to our dynamics.  Solar is a software infrastructure designed to
    deliver contextual information to these applications.  Solar
    represents context data as events, and uses small programs called
    operators to filter, merge, aggregate, or transform event streams.
    This paper explores the possibility of using XSLT and XQuery to build
    language-neutral Solar operators. 
  }
}

@TechReport{Dartmouth:TR2002-430,
  author = {Eileen Zishuang Ye},
  title = {{Building Trusted Paths for Web Browsers}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-430},
  year = {2002},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-430.ps.Z},
  abstract = {
    	The communication between the Web browser and the human
    user is one component of the server-client channel. It is not
    the user but the browser that receives all server
    information and establishes the secure connection. The
    browser's user interface signals, such as SSL lock, https
    protocol header et al., indicate whether the browser-server
    communication at the current moment is secure. Those
    user interface signals indicating the security status of
    browser should be clearly and correctly understood by the
    user.
           A survey of modern Web browsers shows the information
    provided by current browsers is insufficient for users to
    make trust judgment. Our Web spoofing work further proved
    that the browser status information is not reliable either.
           We discuss the criteria for and how to build the
    trusted paths between a browser and a human user. We present
    an open source implementation of one of the
    designs--synchronized random dynamic (SRD) boundary, based
    on Modified Mozilla source code, together with its usability
    study results.
  }
}

@TechReport{Dartmouth:TR2002-431,
  author = {Kobby Essien},
  title = {{Analysis of Protein Sequences Using Time Frequency and  Kolmogorov-Smirnov Methods}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-431},
  year = {2002},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-431.ps.Z},
  comment = {
    Senior Honors Thesis.  Advisor: Metin Akay.<br>
  },
  abstract = {
    The plethora of genomic data currently available has resulted in a 
    search for new algorithms and analysis techniques to interpret 
    genomic data.  In this two-fold study we explore techniques for 
    locating critical amino acid residues in protein sequences and for 
    estimating the similarity between proteins.  We demonstrate the use 
    of the Short-Time Fourier Transform and the Continuous Wavelet 
    Transform together with amino acid hydrophobicity in locating 
    important amino acid domains in proteins and also show that the 
    Kolmogorov-Smirnov statistic can be used as a metric of protein 
    similarity.
  }
}

@TechReport{Dartmouth:TR2002-432,
  author = {David Kotz and Kobby Essien},
  title = {{Analysis of a Campus-wide Wireless Network}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-432},
  year = {2002},
  month = {September},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-432.ps.Z},
  comment = {
    This paper is a revision of the MOBICOM '02 paper by the same
    title.  The only difference is the correction of Figures 27-28
    and the associated text.  This report supplants TR2002-423.
  },
  abstract = {
    Understanding usage patterns in wireless local-area networks (WLANs)
    is critical for those who develop, deploy, and manage WLAN technology,
    as well as those who develop systems and application software for
    wireless networks.  This paper presents results from the largest and
    most comprehensive trace of network activity in a large, production
    wireless LAN.  For eleven weeks we traced the activity of nearly two
    thousand users drawn from a general campus population, using a
    campus-wide network of 476 access points spread over 161 buildings.
    Our study expands on those done by Tang and Baker, with a
    significantly larger and broader population.
      We found that residential traffic dominated all other traffic,
    particularly in residences populated by newer students; students are
    increasingly choosing a wireless laptop as their primary computer.
    Although web protocols were the single largest component of traffic
    volume, network backup and file sharing contributed an unexpectedly
    large amount to the traffic.  Although there was some roaming within a
    network session, we were surprised by the number of situations in
    which cards roamed excessively, unable to settle on one access point.
    Cross-subnet roams were an especial problem, because they broke IP
    connections, indicating the need for solutions that avoid or
    accommodate such roams.
  }
}

@TechReport{Dartmouth:TR2002-433,
  author = {Ron Oldfield and David Kotz},
  title = {{Using the Emulab network testbed to evaluate the Armada I/O  framework for computational grids}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-433},
  year = {2002},
  month = {September},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-433.ps.Z},
  abstract = {
    This short report describes our experiences using the Emulab network testbed 
    at the University of Utah to test performance of the Armada framework for 
    parallel I/O on computational grids. 
    
  }
}

@TechReport{Dartmouth:TR2002-434,
  author = {Ryan H. Lilien and Hany Farid and Bruce R. Donald},
  title = {{Probabilistic Disease Classification of Expression-Dependent Proteomic Data from Mass Spectrometry of Human Serum}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-434},
  year = {2002},
  month = {October},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-434.ps.Z},
  comment = {
    To appear in <em>Journal of Computational Biology</em> (2003).
  },
  abstract = {
      We have developed an algorithm called Q5 for probabilistic
    classification of healthy vs. disease whole serum samples using mass
    spectrometry. The algorithm employs Principal Components Analysis (PCA)
    followed by Linear Discriminant Analysis (LDA) on whole spectrum
    Surface-Enhanced Laser Desorption/Ionization Time of Flight
    (SELDI-TOF) Mass Spectrometry (MS) data, and is demonstrated on four
    real datasets from complete, complex SELDI spectra of human blood
    serum.
      Q5 is a closed-form, exact solution to the problem of classification
    of complete mass spectra of a complex protein mixture. Q5 employs a
    novel probabilistic classification algorithm built upon a
    dimension-reduced linear discriminant analysis.  Our solution is
    computationally efficient; it is non-iterative and computes the
    optimal linear discriminant using closed-form equations. The optimal
    discriminant is computed and verified for datasets of complete,
    complex SELDI spectra of human blood serum. Replicate experiments of
    different training/testing splits of each dataset are employed to
    verify robustness of the algorithm. The probabilistic classification
    method achieves excellent performance. We achieve sensitivity,
    specificity, and positive predictive values above 97% on three
    ovarian cancer datasets and one prostate cancer dataset. The Q5 method
    outperforms previous full-spectrum complex sample spectral
    classification techniques, and can provide clues as to the molecular
    identities of differentially-expressed proteins and peptides.
  }
}

@TechReport{Dartmouth:TR2002-435,
  author = {Qun Li and Michael De Rosa and Daniela Rus},
  title = {{Distributed Algorithms for Guiding Navigation across a Sensor Network}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-435},
  year = {2002},
  month = {October},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-435.ps.Z},
  abstract = {
    We develop distributed algorithms for self-reconfiguring sensor
    networks that respond to directing a target through a region. The
    sensor network models the danger levels sensed across its area and has
    the ability to adapt to changes. It represents the dangerous areas as
    obstacles. A protocol that combines the artificial potential field of
    the sensors with the goal location for the moving object guides the
    object incrementally across the network to the goal, while maintaining
    the safest distance to the danger areas. We report on hardware
    experiments using a physical sensor network consisting of Mote
    sensors.
  }
}

@TechReport{Dartmouth:TR2002-436,
  author = {Robert C. Fitch},
  title = {{Heterogeneous Self-Reconfiguring Robotics}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-436},
  year = {2002},
  month = {November},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-436.ps.Z},
  abstract = {
      Self-reconfiguring robots are modular systems that can change shape,
    or "reconfigure," to match structure to task. They comprise many
    small, discrete, often identical modules that connect together and
    that are minimally actuated. Global shape transformation is achieved
    by composing local motions. Systems with a single module type, known
    as "homogeneous" systems, gain fault tolerance, robustness and low
    production cost from module interchangeability. However, we are
    interested in "heterogeneous" systems, which include multiple types of
    modules such as those with sensors, batteries or wheels.  We believe
    that heterogeneous systems offer the same benefits as homogeneous
    systems with the added ability to match not only structure to task,
    but also capability to task.
       Although significant results have been achieved in understanding
    homogeneous systems, research in heterogeneous systems is challenging
    as key algorithmic issues remain unexplored. We propose in this thesis
    to investigate questions in four main areas: 1) how to classify
    heterogeneous systems, 2) how to develop efficient heterogeneous
    reconfiguration algorithms with desired characteristics, 3) how to
    characterize the complexity of key algorithmic problems, and 4) how to
    apply these heterogeneous algorithms to perform useful new tasks in
    simulation and in the physical world. Our goal is to develop an
    algorithmic basis for heterogeneous systems. This has theoretical
    significance in that it addresses a major open problem in the field,
    and practical significance in providing self-reconfiguring robots with
    increased capabilities.
  }
}

@TechReport{Dartmouth:TR2002-437,
  author = {Heng Huang and Chris Hawblitzel},
  title = {{Proofs of Soundness and Strong Normalization for Linear Memory Types}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-437},
  year = {2002},
  month = {November},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-437.ps.Z},
  abstract = {
    Efficient low-level systems need more control over memory than safe high-level languages usually provide. As a result, run-time systems are typically written in unsafe languages such as C. This report describes an abstract machine designed to give type-safe code more control over memory. It includes complete definitions and proofs.
  }
}

@TechReport{Dartmouth:TR2002-438,
  author = {Valentino Crespi},
  title = {{Exact formulae for the Lovasz Theta Function of sparse Circulant Graphs}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2002-438},
  year = {2002},
  month = {November},
  URL = {http://www.cs.dartmouth.edu/reports/TR2002-438.ps.Z},
  abstract = {
      The Lovasz theta function has attracted a lot of attention for its
    connection with diverse issues, such as communicating without errors
    and computing large cliques in graphs. Indeed this function enjoys the
    remarkable property of being computable in polynomial time, despite
    being sandwitched between clique and chromatic number, two well known
    hard to compute quantities.
      In this paper I provide a closed formula for the Lovasz function of a
    specific class of sparse circulant graphs thus generalizing Lovasz
    results on cycle graphs (circulant graphs of degree 2).
  }
}

@TechReport{Dartmouth:TR2003-439,
  author = {Chris J. Langmead and Bruce R. Donald},
  title = {{3D-Structural Homology Detection via Unassigned Residual Dipolar Couplings}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-439},
  year = {2003},
  month = {January},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-439.pdf},
  comment = {
    A revised and expanded version of this TR will appear as a refereed
    paper at the 
    <a href="http://conferences.computer.org/bioinformatics/">
    IEEE Computer Society Bioinformatics Conference
    </a>,
    Stanford, California (August, 2003),
  },
  abstract = {
         Recognition of a protein's fold provides valuable
    information about its function.  While many sequence-based
    homology prediction methods exist, an important challenge remains:
    two highly dissimilar sequences can have similar folds --- how can
    we detect this rapidly, in the context of structural genomics?
    High-throughput NMR experiments, coupled with novel algorithms for
    data analysis, can address this challenge. We report an automated
    procedure for detecting 3D-structural homologies from sparse,
    unassigned protein NMR data.
         Our method identifies the 3D-structural models in a protein
    structural database whose geometries best fit the unassigned
    experimental NMR data. It does not use sequence information and is
    thus not limited by sequence homology.  The method can also be
    used to confirm or refute structural predictions made by other
    techniques such as protein threading or sequence homology. The
    algorithm runs in O(pnk<sup>3</sup>) time, where p is the number of
    proteins in the database, n is the number of residues in the
    target protein, and k is the resolution of a rotation search.
    The method requires only uniform 15N-labelling of the protein
    and processes unassigned 1H-15N residual dipolar couplings,
    which can be acquired in a couple of hours. Our experiments on NMR
    data from 5 different proteins demonstrate that the method
    identifies closely related protein folds, despite low-sequence
    homology between the target protein and the computed
    model.
  }
}

@TechReport{Dartmouth:TR2003-440,
  author = {David M. Nicol and Sean W. Smith and Meiyuan Zhao},
  title = {{Efficient Security for BGP Route Announcements}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-440},
  year = {2003},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-440.R2.ps.Z},
  comment = {
    Revision 2 released May 9, 2003.  
    Original revision 1, of February 2003, is available in 
    <a href=http://www.cs.dartmouth.edu/reports/TR2003-440.R1.pdf>pdf</a> or 
    <a href=http://www.cs.dartmouth.edu/reports/TR2003-440.R1.ps.Z>ps.Z</a>.
  },
  abstract = {
    The Border Gateway Protocol (BGP) determines how Internet traffic is
    routed throughout the entire world; malicious behavior by one or more
    BGP speakers could create serious security issues. Since the protocol
    depends on a speaker honestly reporting path information sent by
    previous speakers and involves a large number of independent speakers,
    the Secure BGP (S-BGP) approach uses public-key cryptography to ensure
    that a malicious speaker cannot fabricate this information. However,
    such public-key cryptography is expensive: S-BGP requires a digital
    signature operation on each announcement sent to each peer, and a
    linear (in the length of the path) number of verifications on each
    receipt. We use simulation of a 110 AS system derived from the
    Internet to evaluate the impact that the processing costs of
    cryptography have on BGP convergence time. We find that under heavy
    load the convergence time using ordinary S-BGP is nearly twice as
    large as under BGP. We examine the impact of highly aggressive caching
    and pre-computation optimizations for S-BGP, and find that convergence
    time is much closer to BGP. However, these optimizations may be
    unrealistic, and are certainly expensive of memory. We consequently
    use the structure of BGP processing to design optimizations that
    reduce cryptographic overhead by amortizing the cost of private-key
    signatures over many messages. We call this method
    Signature-Amortization (S-A). We find that S-A provides as good or
    better convergence times as the highly optimized S-BGP, but without
    the cost and complications of caching and pre-computation. It is
    possible therefore to minimize the impact route validation has on
    convergence, by being careful with signatures, rather than consumptive
    of memory.  
  }
}

@TechReport{Dartmouth:TR2003-441,
  author = {Yasir Ali and S. W. Smith},
  title = {{Flexible and Scalable Public Key Security for SSH}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-441},
  year = {2003},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-441.pdf},
  comment = {
    A revised version, published as a conference paper, as follows:
    <br>Y. Ali, S.W. Smith.
    <br>"Flexible and Scalable Public Key Security for SSH."
    <br>Public Key Infrastructure: EuroPKI 2004, pp. 43-56,
    <br>LNCS 3093, June 2004. Springer-Verlag. DOI 10.1007/b98201.
    <br>http://dx.doi.org/10.1007/b98201
    <br>http://www.springerlink.com/content/h8jng6kc1rf3j97g/
  },
  abstract = {
    A standard tool for secure remote access, the SSH protocol uses public-key cryptography to establish an encrypted and integrity-protected channel with a remote server. However, widely-deployed implementations of the protocol are vulnerable to man-in-the-middle attacks, where an adversary substitutes her public key for the server's. This danger particularly threatens a traveling user Bob borrowing a client machine.
       Imposing a traditional X.509 PKI on all SSH servers and clients is neither flexible nor scalable nor (in the foreseeable future) practical. Requiring extensive work or an SSL server at Bob's site is also not practical for many users.
       This paper presents our experiences designing and implementing an alternative scheme that solves the public-key security problem in SSH without requiring such an a priori universal trust structure or extensive sysadmin work--although it does require a modified SSH client. (The code is available for public download.)
  }
}

@TechReport{Dartmouth:TR2003-442,
  author = {Alex Iliev and Sean Smith},
  title = {{Privacy-enhanced credential services}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-442},
  year = {2003},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-442.ps.Z},
  comment = {
    Submitted to the 2nd Annual PKI Research Workshop.
  },
  abstract = {
    The use of credential directories in PKI and authorization systems such as
    Shibboleth introduces a new privacy risk: an insider at the directory can learn
    much about otherwise protected interactions by observing who makes queries, and
    what they ask for.  Recent advances in Practical Private Information Retrieval
    provide promising countermeasures.  In this paper, we extend this technology to
    solve this new privacy problem, and present a design and preliminary prototype
    for a LDAP-based credential service that can prevent even an insider from
    learning anything more than the fact a query was made.  Our preliminary
    performance analysis suggests that the complete prototype may be sufficiently
    robust for academic enterprise settings.
  }
}

@TechReport{Dartmouth:TR2003-443,
  author = {John C. Marchesini and Sean W. Smith and Meiyuan Zhao},
  title = {{Keyjacking: Risks of the Current Client-side Infrastructure}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-443},
  year = {2003},
  month = {February},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-443.ps.Z},
  abstract = {
    In theory, PKI can provide a flexible and strong way to
    authenticate users in distributed information systems. In practice,
    much is being invested in realizing this vision via client-side SSL
    and browser-based keystores. Exploring this vision, we demonstrate
    that browsers will use personal certificates to authenticate requests
    that the person neither knew of nor approved (and which password-based
    systems would have defeated), and we demonstrate the easy permeability
    of these keystores (including new attacks on medium and high-security
    IE/XP keys). We suggest some countermeasures, but also suggest that a
    fundamental rethinking of the trust, usage, and storage model might
    result in a more effective PKI.
  }
}

@TechReport{Dartmouth:TR2003-444,
  author = {Geeta Chaudhry and Thomas H. Cormen},
  title = {{Stupid Columnsort Tricks}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-444},
  year = {2003},
  month = {April},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-444.ps.Z},
  abstract = {
    Leighton's columnsort algorithm sorts on an $r \times s$ mesh, subject
    to the restrictions that $s$ is a divisor of~$r$ and that $r \geq
    2s^2$ (so that the mesh is tall and thin).  We show how to mitigate
    both of these restrictions.  One result is that the requirement that
    $s$ is a divisor of~$r$ is unnecessary; columnsort sorts correctly
    whether or not $s$ divides~$r$.  We present two algorithms that, as
    long as $s$ is a perfect square, relax the restriction that $r \geq
    2s^2$; both reduce the exponent of~$s$ to~$3/2$.  One algorithm
    requires $r \geq 4s^{3/2}$ if $s$ divides~$r$ and $r \geq 6s^{3/2}$ if
    $s$ does not divide~$r$.  The other algorithm requires $r \geq
    4^{3/2}$, and it requires $s$ to be a divisor of~$r$.  Both algorithms
    have applications in increasing the maximum problem size in
    out-of-core sorting programs.
  }
}

@TechReport{Dartmouth:TR2003-445,
  author = {Geeta Chaudhry and Elizabeth A. Hamon and Thomas H. Cormen},
  title = {{Relaxing the Problem-Size Bound for Out-of-Core Columnsort}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-445},
  year = {2003},
  month = {April},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-445.ps.Z},
  abstract = {
    Previous implementations of out-of-core columnsort limit the problem
    size to $N \leq \sqrt{(M/P)^3 / 2}$, where $N$ is the number of
    records to sort, $P$ is the number of processors, and $M$ is the total
    number of records that the entire system can hold in its memory (so
    that $M/P$ is the number of records that a single processor can hold
    in its memory).  We implemented two variations to out-of-core
    columnsort that relax this restriction.  Subblock columnsort is based
    on an algorithmic modification of the underlying columnsort algorithm,
    and it improves the problem-size bound to $N \leq (M/P)^{5/3} /
    4^{2/3}$ but at the cost of additional disk I/O\@.  $M$-columnsort
    changes the notion of the column size in columnsort, improving the
    maximum problem size to $N \leq \sqrt{M^3 / 2}$ but at the cost of
    additional computation and communication.  Experimental results on a
    Beowulf cluster show that both subblock columnsort and $M$-columnsort
    run well but that $M$-columnsort is faster.  A further advantage of
    $M$-columnsort is that it handles a wider range of problem sizes than
    subblock columnsort.
  }
}

@TechReport{Dartmouth:TR2003-446,
  author = {Prasad Jayanti and Srdjan Petrovic},
  title = {{Efficient and Practical Constructions of LL/SC Variables}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-446},
  year = {2003},
  month = {June},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-446.pdf},
  abstract = {
    Over the past decade, LL/SC have emerged as the most suitable
    synchronization instructions for the design of lock-free algorithms.
    However, current architectures do not support these instructions;
    instead, they support either CAS or RLL/RSC (e.g. POWER4, MIPS, SPARC, IA-64). To bridge this gap, this paper presents two efficient wait-free
    algorithms for implementing 64-bit LL/SC objects from 64-bit CAS or
    RLL/RSC objects.
       Our first algorithm is practical: it has a small, constant time complexity (of 4 for LL and 5 for SC) and a space overhead of only 4 words per process. This algorithm uses unbounded sequence numbers.
    For theoretical interest, we also present a more complex bounded algorithm
    that still guarantees constant time complexity and O(1) space overhead per process.
       The LL/SC primitive is free of the well-known ABA problem that afflicts CAS. By efficiently implementing LL/SC words from CAS words,
    this work presents an efficient general solution to the ABA problem.
  }
}

@TechReport{Dartmouth:TR2003-448,
  author = {Thomas Mueller},
  title = {{Billiards Adviser as a Search in a Continuous Domain with Significant Uncertainty}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2003-448},
  year = {2003},
  month = {May},
  URL = {http://www.cs.dartmouth.edu/reports/TR2003-448.pdf},
  comment = {
    Advisor: Zack Butler
  },
  abstract = {
    Typical search algorithms are limited to problems in which there is a certain number of moves for any given state, and the effect of each move is well known.  In order to overcome this limitation, we consider the problem of determining the optimal shot given the positions of balls on a billiards table.  Our solution includes the image recognition necessary to determine each ball's position, the calculation of the optimal shot, and the presentation of that shot to the player.  The focus of the paper is on the second part - determining the angle and force with which the player should attempt to hit the cue ball for each shot in order to sink all of the other balls with the fewest shots.  The solution to this problem is unique from other game search algorithms in that it must take into account the infinite number of possible shots given any configuration of balls as well as the fact that the player is not likely to hit the ball exactly how he attempts to do so.  We compare the performance of our algorithm with one that ignores the latter fact to show that our modifications do in fact improve performance for a search in a continuous domain with significant uncertainty.
  }
}

@TechReport{Dartmouth:TR2003-449,
  author = {Lisa A. Torrey},
  title = {{An Active Learning Approach to Efficiently Ranking Retrieval Engines}},
  institution = {Dartmouth College, Computer Science},