TY - JOUR

T1 - Tight Lower Bounds on the Resolution Complexity of Perfect Matching Principles

AU - Itsykson, Dmitry

AU - Oparin, Vsevolod

AU - Slabodkin, Mikhail

AU - Sokolov, Dmitry

PY - 2016/1/1

Y1 - 2016/1/1

N2 - The resolution complexity of the perfect matching principle was studied by Razborov [1], who developed a technique for proving its lower bounds for dense graphs. We construct a constant degree bipartite graph Gn such that the resolution complexity of the perfect matching principle for Gn is 2Ω(n) where n is the number of vertices in Gn. This lower bound is tight up to some polynomial. Our result implies the 2Ω(n) lower bounds for the complete graph K2n + 1 and the complete bipartite graph Kn,O(n) that improves the lower bounds following from [1]. We show that for every graph G with n vertices that has no perfect matching there exists a resolution refutation of perfect matching principle for G of size O(n22n). Thus our lower bounds match upper bounds up to a multiplicative constant in the exponent. Our results also imply the well-known exponential lower bounds on the resolution complexity of the pigeonhole principle, the functional pigeonhole principle and the pigeonhole principle over a graph. We also prove the following corollary. For every natural number d, for every n large enough, for every function h: {1, 2,., n} → {1, 2,., d}, we construct a graph with n vertices that has the following properties. There exists a constant D such that the degree of the i-Th vertex is at least h(i) and at most D, and it is impossible to make all degrees equal to h(i) by removing the graph's edges. Moreover, any proof of this statement in the resolution proof system has size 2Ω(n). This result implies well-known exponential lower bounds on the Tseitin formulas as well as new results: for example, the same property of a complete graph. Preliminary version of this paper appeared in proceedings of CSR-2015 [2].

AB - The resolution complexity of the perfect matching principle was studied by Razborov [1], who developed a technique for proving its lower bounds for dense graphs. We construct a constant degree bipartite graph Gn such that the resolution complexity of the perfect matching principle for Gn is 2Ω(n) where n is the number of vertices in Gn. This lower bound is tight up to some polynomial. Our result implies the 2Ω(n) lower bounds for the complete graph K2n + 1 and the complete bipartite graph Kn,O(n) that improves the lower bounds following from [1]. We show that for every graph G with n vertices that has no perfect matching there exists a resolution refutation of perfect matching principle for G of size O(n22n). Thus our lower bounds match upper bounds up to a multiplicative constant in the exponent. Our results also imply the well-known exponential lower bounds on the resolution complexity of the pigeonhole principle, the functional pigeonhole principle and the pigeonhole principle over a graph. We also prove the following corollary. For every natural number d, for every n large enough, for every function h: {1, 2,., n} → {1, 2,., d}, we construct a graph with n vertices that has the following properties. There exists a constant D such that the degree of the i-Th vertex is at least h(i) and at most D, and it is impossible to make all degrees equal to h(i) by removing the graph's edges. Moreover, any proof of this statement in the resolution proof system has size 2Ω(n). This result implies well-known exponential lower bounds on the Tseitin formulas as well as new results: for example, the same property of a complete graph. Preliminary version of this paper appeared in proceedings of CSR-2015 [2].

KW - expander

KW - perfect matching

KW - proof complexity

KW - resolution

KW - width

UR - http://www.scopus.com/inward/record.url?scp=84984917469&partnerID=8YFLogxK

U2 - 10.3233/FI-2016-1358

DO - 10.3233/FI-2016-1358

M3 - Article

AN - SCOPUS:84984917469

VL - 145

SP - 229

EP - 242

JO - Fundamenta Informaticae

JF - Fundamenta Informaticae

SN - 0169-2968

IS - 3

ER -