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]
8
 
Thu Oct 09 Theorems of Adleman and Sipser-Gacs; RL, BPL, NC, RNC: USTCON and MATCH [AB: 7]
X
 
Fri Oct 10 Not used
9
 
Tue Oct 14 Randomized reductions: Valiant-Vazirani Theorem [AB: 7, 17]
10
 
Thu Oct 16 Foundations of cryptography; one-way functions, pseudorandom generators [AB: 9]
X
 
Fri Oct 17 Not used
11
 
Tue Oct 21 Unpredictability and PRGs; Yao's hybrid argument; Goldreich-Levin Theorem [AB: 9]
12
 
Thu Oct 23 One-way permutations to PRGs; Applications: telephone poker, encryption [AB: 9]
  (notes)
X
 
Fri Oct 24 Not used
Phase 3: The Power of Interaction
13
 
Tue Oct 28 Interactive proofs (IP); Arthur-Merlin games (AM, MA); Graph Non-Isomorphism [AB: 8]
14
 
Thu Oct 30 Goldwasser-Sipser Protocol; GNI and NP-completeness [AB: 8]
  (notes)
15
 
Fri Oct 31 Zero-knowledge proofs [AB: 9.4]
16
 
Tue Nov 04 Arithmetization; LFKN Theorem; Shamir's Theorem (IP = PSPACE) [Sip: 10.4]
17
 
Thu Nov 06 Introduction to PCPs; PCP theorem; Applications [AB: 11]
X
 
Fri Nov 07 TBD
18
 
Tue Nov 11 PCPs and hardness of approximation
19
 
Thu Nov 13 The "Unique Games" Conjecture and applications
X
 
Fri Nov 14 TBD
20
 
Tue Nov 18 Wrap-up