CS 40/240: Computational Complexity
Fall 2025 | 10A hour (TTh 10:10-12:00, x-hr F 15:30-16:20) | Cummings 118
Professor Amit Chakrabarti

Topics and Events, Day by Day

The table below will be updated throughout the term.

Any content that's colored light gray is tentative and subject to change.

 

Phase 1: Delving deeper into Nondeterminism, Time and Space
1
 
Tue Sep 16 Review of languages and Turing Machines, DTIME, NTIME [Sip: 3,4,5,7]
  (notes)
2
 
Thu Sep 18 Review of NP-completeness and reductions [Sip: 3,4,5,7]
  (notes)
X
 
Fri Sep 19 Special session: are you ready for this course?
3
 
Tue Sep 23 Space complexity; Savitch's Theorem; PSPACE and PSPACE-completeness [Sip: 8]
  (notes)
4
 
Thu Sep 25 Sublinear space (N, NL); Logspace reductions; NL-completeness; Immerman-Szelepcsenyi (NL = coNL) [Sip: 8]
  (notes)
X
 
Fri Sep 26 Not used
5
 
Tue Sep 30 Hierarchy theorems: space and time; Polynomial hierarchy (PH) [Sip: 9], [AB: 3, 5]
6
 
Thu Oct 02 Circuits; Non-uniformity; Shannon's Theorem; Karp-Lipton Theorem [AB: 6]
  (notes)
X
 
Fri Oct 03 Catch up
Phase 2: The Power of Randomness
7
 
Tue Oct 07 Randomization: RP, coRP, BPP; Examples: Primality, PIT; Schwartz-Zippel [AB: 7]
X
 
Thu Oct 09 TBD
8
 
Fri Oct 10 More examples: USTCON, Matching; Adleman's Theorem [AB: 7]
9
 
Tue Oct 14 Sipser-Gacs Theorem; Randomized reduction; Valiant-Vazirani Theorem
X
 
Thu Oct 16 TBD
10
 
Fri Oct 17 Foundations of cryptography; one-way functions, pseudorandom generators
11
 
Tue Oct 21 Next-bit unpredictability; Yao's hybrid argument; Goldreich-Levin Theorem
X
 
Thu Oct 23 TBD
12
 
Fri Oct 24 Goldreich-Levin Theorem: One-way permutations to PRGs
Phase 3: The Power of Interaction
13
 
Tue Oct 28 Interactive proofs (IP); Arthur-Merlin games (AM); Graph Non-Isomorphism
X
 
Thu Oct 30 TBD
14
 
Fri Oct 31 Goldwasser-Sipser Protocol; GNI and NP-completeness
15
 
Tue Nov 04 Arithmetization; LFKN Theorem; Shamir's Theorem (IP = PSPACE)
X
 
Thu Nov 06 TBD
16
 
Fri Nov 07 Introduction to PCPs; PCP theorem; Applications
17
 
Tue Nov 11 PCPs and hardness of approximation
18
 
Thu Nov 13 The "Unique Games" Conjecture and applications