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Optimal Sparsification for Some Binary CSPs Using Low-Degree Polynomials

Optimal Sparsification for Some Binary CSPs Using Low-Degree Polynomials This article analyzes to what extent it is possible to efficiently reduce the number of clauses in NP-hard satisfiability problems without changing the answer. Upper and lower bounds are established using the concept of kernelization. Existing results show that if NP coNP/poly, no efficient preprocessing algorithm can reduce n-variable instances of cnf-sat with d literals per clause to equivalent instances with  O(ndε ) bits for any ε > 0. For the Not-All-Equal sat problem, a compression to size (nd1) exists. We put these results in a common framework by analyzing the compressibility of CSPs with a binary domain. We characterize constraint types based on the minimum degree of multivariate polynomials whose roots correspond to the satisfying assignments, obtaining (nearly) matching upper and lower bounds in several settings. Our lower bounds show that not just the number of constraints, but also the encoding size of individual constraints plays an important role. For example, for Exact Satisfiability with unbounded clause length it is possible to efficiently reduce the number of constraints to  n+1, yet no polynomial-time algorithm can reduce to an equivalent instance with  O(n2ε ) bits for any  ε > 0, unless NP coNP/poly. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png ACM Transactions on Computation Theory (TOCT) Association for Computing Machinery

Optimal Sparsification for Some Binary CSPs Using Low-Degree Polynomials

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Publisher
Association for Computing Machinery
Copyright
Copyright © 2019 ACM
ISSN
1942-3454
eISSN
1942-3462
DOI
10.1145/3349618
Publisher site
See Article on Publisher Site

Abstract

This article analyzes to what extent it is possible to efficiently reduce the number of clauses in NP-hard satisfiability problems without changing the answer. Upper and lower bounds are established using the concept of kernelization. Existing results show that if NP coNP/poly, no efficient preprocessing algorithm can reduce n-variable instances of cnf-sat with d literals per clause to equivalent instances with  O(ndε ) bits for any ε > 0. For the Not-All-Equal sat problem, a compression to size (nd1) exists. We put these results in a common framework by analyzing the compressibility of CSPs with a binary domain. We characterize constraint types based on the minimum degree of multivariate polynomials whose roots correspond to the satisfying assignments, obtaining (nearly) matching upper and lower bounds in several settings. Our lower bounds show that not just the number of constraints, but also the encoding size of individual constraints plays an important role. For example, for Exact Satisfiability with unbounded clause length it is possible to efficiently reduce the number of constraints to  n+1, yet no polynomial-time algorithm can reduce to an equivalent instance with  O(n2ε ) bits for any  ε > 0, unless NP coNP/poly.

Journal

ACM Transactions on Computation Theory (TOCT)Association for Computing Machinery

Published: Aug 31, 2019

Keywords: Constraint satisfaction problem

References