Title
Tight Size-Degree Bounds for Sums-of-Squares Proofs.
Abstract
We exhibit families of 4-CNF formulas over n variables that have sums-of-squares (SOS) proofs of unsatisfiability of degree (a.k.a. rank) d but require SOS proofs of size ({n^{Omega{(d)}}}) for values of d = d(n) from constant all the way up to ({n^{delta}}) for some universal constant ({delta}). This shows that the ({{n^{{rm O}{(d)}}}}) running time obtained by using the Lasserre semidefinite programming relaxations to find degree-d SOS proofs is optimal up to constant factors in the exponent. We establish this result by combining NP-reductions expressible as low-degree SOS derivations with the idea of relativizing CNF formulas in Krajicek (Arch Math Log 43(4):427–441, 2004) and Dantchev u0026 Riis (Proceedings of the 17th international workshop on computer science logic (CSL ’03), 2003) and then applying a restriction argument as in Atserias et al. (J Symb Log 80(2):450–476, 2015; ACM Trans Comput Log 17:19:1–19:30, 2016). This yields a generic method of amplifying SOS degree lower bounds to size lower bounds and also generalizes the approach used in Atserias et al. (2016) to obtain size lower bounds for the proof systems resolution, polynomial calculus, and Sherali–Adams from lower bounds on width, degree, and rank, respectively.
Year
DOI
Venue
2015
10.1007/s00037-017-0152-4
Conference on Computational Complexity
Keywords
DocType
Volume
Proof complexity,resolution,Lasserre,Positivstellensatz,sums-of-squares,SOS,semidefinite programming,size,degree,rank,clique,lower bound
Journal
26
Issue
ISSN
Citations 
4
1016-3328
1
PageRank 
References 
Authors
0.36
25
2
Name
Order
Citations
PageRank
Massimo Lauria112214.73
Jakob Nordström217721.76