Complexity course outline Spring 1999

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

Date Type Topics reference handouts
March 29 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
April 8 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
April 14 Targil* 1 O-notations: definitions. Turing machines: 1-tape TM for palindrome identification. P chapter 2.1-2.3. Exercise 1
April 19 Lecture 3 Random Access Machine: definition and examples. Polynomial equivalence of RAM and TM. Nondeterministic Machines (incomplete) P 2.6 Exercise 2
April 22 Lecture 4 nondeterministic machines, proper complexity functions, complexity classes, complementary classes, universal Turing machines 2.7, 7.1 -
April 23 Lecture 5 Time and Space Hierarchy theorems, Gap theorem (w/o proof), relations between deterministic and nondeterministic complexity classes (incomplete); 7.1 7.2 -
April 23 Lecture 6 relations between deterministic and nondeterministic complexity classes, Savitch's theorem; the configuration graph, the reachability method, Immerman's theorem. Reductions (incomplete). 7.3 -
April 23 Targil 2 Simulating DTM by a DTM with fixed alphabet. - -
April 26 Lecture 7 Reductions; Hamlitonian Path < SAT; Circuit SAT < SAT; reduction by generalization Transitivity of (logspace) reductions; 8.1 -
April 28 Targil 3 Equivalent definitions of NP P chapter 9.1 Exercise 3, Solutions to ex. 1
April 29 Lecture 8 Completeness; Circuit Value is P-complete (two proofs) Cook's Theorem (2 proofs) 8.1 8.2, JaJa 10.5 Outline of JaJa's reduction, Outline of Cook's theorem a-la Even
May 3 Lecture 9 variation of SAT: 3SAT, 3 occurences per variable. SAT < Independet Set; SAT < Hypergraph 2-colorability Hypergraph 2-colorability: restrictions; Set Splitting; Not-All-Equal SAT; 3SAT < MAX2SAT 8.2 9.1 Even 9.3 my notes
May 6 Lecture 10 3SAT < Directed Hamiltonian Cycle DHC reduction from Hopcroft-Ullman simplified figure for the DHC reduction
May 10 Lecutre 11 3SAT < 3DM , X3C GJ 3.1.2 3DM reduction summary and sketch
May 13 Lecture 12 NAE-3SAT < Max Cut; Max Bisection, Bisection width. X3C < Subset Sum; Subset Sum < Partition. Dynamic Programming algorithm for Subset Sum. P 9.1; 9.2; GJ 3.1.5 simplified -
May 19 Targil 4 NAE-3SAT < 3-COLORING; 3-SAT < E3-SAT; UHC < UHP P 9.3 Exercise 4, Solutions to ex. 2
May 24 Lecture 13 Number problems; Pseudopolynomial algorithms; strong NP-completeness; Pseudopolynomial reductions; GJ 4.2 -
May 26 Targil 5 DHC < UHC; CVP < LP(D); Bin-Packing with constant number of bins JaJa p. 552 Exercise 5, Solutions to ex. 3
May 27 Lecture 14 Bin Packing is Strongly NP-complete (redcution from 3DM); 3-Partition (w/o proof); Interval Sequencing: Pseudo polynomial reduction from Bin Packing Subgraph Isomorphism is NPC; Subforest isomorphism: pseudo-polynomial reduction from bin packing.
P 9.4, GJ 4.2.2 -
May 31 Lecutre 15 Dynamic Programming: order of matrix multiplication; TSP;
coNP, the intersection of NP and coNP, Primality and Pratt's theorem (w/o proof)
GJ 4.2.2,
AHU 2.8, BB p. 159;
P 10
-
Jun 2 Targil 6 Characterization of the intersection of NP and CoNP. Polynomial algorithm for coloring a 3-Colorabale graph with O(sqrt |V|) colors; Approximation algorithms for MAX Independen Set in bounded degree graphs. P 13.1 Exercise 6, Solutions to ex. 4
June 3 Lecture 16 Function problems, FP, FNP, reductions between function problems;
Oracle Turing Machines, Turing reductions, NP-hardness; K-th Largest Subset is NP-hard.
P 10,
P 14.3, GJ 5.1;
-
June 7 Lecture 17 Approximation: 1/2-approximation for Bin Packing; First Fit, First Fit Decreasing, Best Fit (w/o proofs); TSP with triangle inequality: 1/3-approximation algorithm. P 13.1, GJ 6.1 -
Jun 9 Targil 7 Approximation algorithm for MAX Independen Set in bounded degree graphs. 2-approximation algorithms for MIN (weight) vertex cover P 13.1 Exercise 7, Solutions to ex. 5
June. 10 Lecture 18 Approximation ratios; Polynomial and fully polynomial time approximation schemes, Absolute approximation for coloring planar graphs. Hardness of approximation: Nonexistence of Absolute approximation for Knapsack, fixed ration for TSP. GJ 6.1, P. 13.1, 13.2 -
June 14 Lecture 19 PCP definition; New (PCP) results on hardness of approximations (w/o proofs). Minimum Equivalent Expression; The Polynomial Heirarchy; Complete problems for levels of the PH. Backtracking example for Hamiltonian Cycle GJ 6.1, P. 13.2
Sedgewick
Backtracking example for Hamiltonian Cycle (Sedgewick)
Jun 16 Targil 8 2-approximation algorithm for MAX CUT. Nonexistence of constant ratio algorithm for MAX Independent Set. - Exercise 8, Solutions to ex. 6
June 17 Lecture 20 Backtracking algorithms: n queens, 3 cloroing. Examples of branch and bound heuristics: TSP, Knapsack.
PSPACE; The Quantified Boolean Formula (QBF) problem; QBF is PSPACE complete;
Sedgewick, BB p. 200
P 19.1
-
June 21 Lecture 21 More PSPACE-complete problems: Geography; In-Place Acceptance.
Counting problems: The class #P, parsimonious reductions; #SAT is #P-complete. Perfect matchings and the permanent. Valiant's Theorem (w/o proof).
Toda's theorem (w/o proof).
Parallel Computations. The PRAM model and its variants. Finding the minimum of n elements in constant parallel time.
P. 19.4,
P. 18.1
-
Jun 23 Targil 9 QBF is in PSPACE.
Sigma_i = Pi_i implies that PH=Sigma_i
P 17.2 Solutions to ex. 7
June 24 Lecture 22 Parallel algorithms for matrix multiplications, Reachability.
NC; Logarithmic space;
In pursuit of the P?NP question (review)
P. 15.1 15.2
GJ 7.6 P 14
*Targil=recitation (in Hebrew)

< = 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).
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