Complexity course outline Spring 2000

Lectures given by Prof. Ron Shamir
Recitations given by Dekel Tsur

Date Type Topics reference handouts
Feb. 21 Lecture 1 Introduction, Algorithms, growth rate of fuctions. Reachability; Max Flow; Matching; The Travelling Salesman Problem. P chapter 1, GJ 1.3 whitepaper and syllabus
Feb 23 Targil* 1 O-notations: definitions. Turing machines: 1-tape TM for palindrome identification. P chapter 2.1-2.3. Exercise 1
TM for palindrome identification.
Feb 24 Lecture 2 Turing Machines: Model, time complexity, k-tape machine, simulation by 1-tape machine; linear speedup theorem; space complexity P 2.1-2.5 my notes
Feb 27 Lecture 3 Random Access Machine: definition and examples. Polynomial equivalence of RAM and TM. P 2.6 -
Feb. 29 Targil 2 Simulating DTM by a DTM with fixed alphabet. - Exercise 2
March 1 Lecture 4 nondeterministic machines, proper complexity functions, 2.7, 7.1 my notes
March 6 Lecture 5 complexity classes, complementary classes, universal Turing machines Time Hierarchy theorem, 7.1 7.2 -
March 8 Targil 3 Equivalent definitions of NP P chapter 9.1 Exercise 3
March 9 Lecture 6 Space Hierarchy theorem, Gap theorem (w/o proof), relations between deterministic and nondeterministic complexity classes, Savitch's theorem; Immerman's theorem 7.3 -
March 13 Lecture 7 Nondeterministic space classes are closed under complement; Reductions; Hamlitonian Path < SAT; Circuit SAT < SAT; reduction by generalization 8.1 -
March 15 Targil 4 P,NP, simple observations. Reachability < CVP. - Exercise 4
March 16 Lecture 8 Transitivity of (logspace) reductions; Completeness; Circuit Value is P-complete (two proofs). Monotone CVP is P-complete. 8.1 8.2, JaJa 10.5 Sketches of recduction (from P.), Outline of JaJa's reduction, Outline of Cook's theorem a-la Even
March 20 Lecture 9 Cook's Theorem (2 proofs);
variation of SAT: 3SAT, 3 occurences per variable. SAT < Independet Set;
SAT < Hypergraph 2-colorability
8.2 9.1 Even 9.3 my notes
March 22 Targil 5 NAE-3SAT < 3-COLORING; SAT < 3-SAT; 3-SAT < E3-SAT P 9.3 Exercise 5
March 23 Lecture 10 Hypergraph 2-colorability: restrictions; Set Splitting; Not-All-Equal SAT; 3SAT < Directed Hamiltonian Cycle DHC reduction from Hopcroft-Ullman simplified figures for the DHC reduction
March 27 Lecutre 11 DHC < TSP
3SAT < 3DM , X3C
GJ 3.1.2 3DM reduction summary and sketch
March 29 Targil 6 E3-SAT < MAX2SAT; DHC < UHC; UHC < UHP; CVP < LP(D) JaJa p. 552 Exercise 6
March 30 Lecture 12 Characterization of NP in terms of Binary relation.
NAE-3SAT < Max Cut; Max Bisection, Bisection width.
X3C < Subset Sum;
P 9.1; 9.2; GJ 3.1.5 simplified -
April 3 Lecture 13 Subset Sum < Partition.
Dynamic Programming algorithm for Subset Sum.
Number problems; Pseudopolynomial algorithms; strong NP-completeness; Pseudopolynomial reductions;
GJ 4.2 -
April 5 Targil 7 IS < IP. P is cloesed under reductions, Space(n) is not. - Exercise 7
April 6 Lecture 14 (IP) Bin Packing is Strongly NP-complete (redcution from 3DM); 3-Partition (w/o proof); Interval Sequencing: Pseudo polynomial reduction from Bin Packing P 9.4, GJ 4.2.2 -
April 10 Lecutre 15 (IP) Subgraph Isomorphism is NPC; Subforest isomorphism: pseudo-polynomial reduction from bin packing.
Dynamic Programming: order of matrix multiplication; TSP; Floyd's algorithm
GJ 4.2.2,
AHU 2.8, BB p. 159;
summary
April 12 Targil 8 Dynamic Programming algorithm for Weighted IS on a path. - Exercise 8
April 13 Lecture 16 (IP) coNP, the intersection of NP and coNP,
Primality and Pratt's theorem
DP for bin packing with two bins
P 10,

Summary
May 1 Lecture 17 Function problems, FP, FNP, reductions between function problems;
Minimum edit distance between sequences
P. 10 Minimum edit distance example from Gusfield's book.
May 3 Targil 9 Characterization of the intersection of NP and CoNP. X3C < EXACTLY ONE SAT. - Exercise 9
May 4 Lecture 18 Total functions: Factoring, Happynet, equal-sum subsets.
Oracle Turing Machines, Turing reductions, NP-hardness; K-th Largest Subset is NP-hard.
Backtracking algorithms: n queens, Backtracking example for Hamiltonian Cycle
P 14.3, GJ 5.1
Sedgewick
Backtracking example for Hamiltonian Cycle (Sedgewick)
May 8 Lecture 19 (RS) Approximation: 1/2-approximation for Bin Packing; First Fit, First Fit Decreasing, Best Fit (w/o proofs);
Approximation ratios; 1/2-approximation for max-sat
GJ 6.1, p 13.1, Mot Ron's slides
May 11 Lecture 20 (RS) TSP with triangle inequality: 1/3-approximation algorithm. Nonexistence of constant ratio approximation for TSP.
Polynomial and fully polynomial time approximation schemes; FPTAS for Knapsack.
P 13.1, GJ 6.1, Mot Ron's slides
May 15 Lecture 21 (RS) Parameterized Complexity:
1 definition of a param. problem.
2. definition of an fpt problem.
3. techniques - bounded search tree and reduction to problem kernel.
4. examples on vertex cover and 3-hitting set.
5. definition of param. reductions.
6. brief review on the W-hierarcy; clique,IS are W[1] complete (w/o proof).
- -
May 17 Targil 10 Approximation algorithm for MAX Independen Set in bounded degree graphs. 2-approximation for MIN weight Vertex Cover. P 13.1 Exercise 10
May 18 Lecture 22 2-approximation for Vertex Cover.
Absolute approximation for coloring planar graphs.
Nonexistence of Absolute approximation for Knapsack.
Branch and bound algorithm for Knapsack.
GJ 6.1, CLR 37.1, 37.4 CLR example, B&B notes and example.
May 22 Lecture 23 Aymptotic approximation ratio
L-reductions: Definitions and properties
L-reduction from IS to VC
MAXSNP and PCP (w/o definitions and proos)
GJ 6.1 P. 13 -
May 24 Targil 11 2-approximation algorithm for MAX CUT. A L-reduction from MAX-3-SAT to MAX IS. - Exercise 11
May 25 Lecture 24 Minimum Equivalent Expression; The Polynomial Heirarchy; Complete problems for levels of the PH.
PSPACE; The Quantified Boolean Formula (QBF) problem, examples of PSPACE complete problems
Branch and bound heuristics for TSP
GJ 6.1, P. 13.2, BB p. 200 PH definitions
TSP branch and bound example
May 29 Lecture 24 QBF is PSPACE complete More PSPACE-complete problems: Geography; In-Place Acceptance.
Counting problems: The class #P, parsimonious reductions; #SAT is #P-complete.
P. 19.4,
P. 18.1
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June 1 Lecture 25 Parallel algorithms for matrix multiplications, Reachability. Parallel computations models: Uniform Boolean Circuits, PRAM. Simulation Theorems (w/o proofs). P. 15.1 15.2
my notes
June 5 Lecture 26 NC
In pursuit of the P?NP question (review)
Course overview
GJ 7.6 P 14
course outline (this document)
June 7 Targil 12 QBF is in PSPACE.
Sigma_i = Pi_i implies that PH=Sigma_i
P 17.2 -
*Targil=recitation (in Hebrew)
IP: Itsik Pe'er; RS: Roded Sharan

< = reduces to (using logarithmic space deterministic Turing Machine)

P= C. Papadimitriou Computational Complexity (Addison Wesley, 1994)
GJ= Garey and Johnson, Computers and Intractability (Freeman, 1979)
AHU= Aho, Hopcroft, and Ullman. The Design and Analysis of Computer Algorithms . (Addison Wesley, Reading, Mass., 1974).
BB= Brassard and Bratley. Algorithmics: Theory and Practice . (Prentice Hall, Englewood Cliffs, N. J., 1988).
CLR= Cormen, Leiserson and Rivest, Introduction to Algorithms (MIT press, 1990)
JaJa = J. JaJa. An Introduction to Parallel Algorithms (Addison-Wesley, Reading, Mass., 1992).
Mot = Rajeev Motwani's Monograph on approximation algorithms
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