Title
Rounding Parallel Repetitions of Unique Games
Abstract
We show a connection between the semidefinite relaxation of unique games and their behavior under parallel repetition. Specifically,denoting by val(G) the value of a two-prover unique game G, andby sdpval(G) the value of a natural semidefinite program to approximate val(G), we prove that for every l epsi N, if sdpval(G) ges 1-delta, then val(Gl) ges 1-radicsldelta. Here, Gl denotes the l-fold parallel repetition of G, and s=O(log(k/delta)), where k denotes the alphabet size of the game. For the special case where G is an XOR game (i.e., k=2), we obtain the same bound but with s as an absolute constant. Our bounds on s are optimal up to a factor of O(log(1/delta)). For games with a significant gap between the quantities val(G) and sdpval(G), our result implies that val(Gl) may be much larger than val(G)l, giving a counterexample to the strong parallel repetition conjecture. In a recent breakthrough, Raz (FOCS'08) has shown such an example using the max-cut game on oddcycles. Our results are based on a generalization of his techniques.
Year
DOI
Venue
2008
10.1109/FOCS.2008.55
FOCS
Keywords
Field
DocType
alphabet size,natural semidefinite program toapproximate,foldparallel repetition,parallel repetition,mathematical programming,semidefinite relaxation,mathbb n,parallel repetitions,computational complexity,game theory,hellinger distance,semidefinite programming,unique games,two-prover unique game,xor game,max-cut game,natural semidefinite program,correlated sampling,strongparallel repetition conjecture,games,probability,computer science,programming
Discrete mathematics,Distance measurement,Combinatorics,Rounding,Game theory,Counterexample,Conjecture,Mathematics,Semidefinite programming,Alphabet,Computational complexity theory
Conference
ISSN
ISBN
Citations 
0272-5428
978-0-7695-3436-7
23
PageRank 
References 
Authors
1.26
16
6
Name
Order
Citations
PageRank
Boaz Barak12563127.61
Moritz Hardt2146082.08
Ishay Haviv3919.86
Anup Rao458132.80
Oded Regev52322133.33
David Steurer693444.91