Resolution over linear equations and multilinear proofs

Ran Raz, Iddo Tzameret

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

We develop and study the complexity of propositional proof systems of varying strength extending resolution by allowing it to operate with disjunctions of linear equations instead of clauses. We demonstrate polynomial-size refutations for hard tautologies like the pigeonhole principle, Tseitin graph tautologies and the clique-coloring tautologies in these proof systems. Using (monotone) interpolation we establish an exponential-size lower bound on refutations in a certain, considerably strong, fragment of resolution over linear equations, as well as a general polynomial upper bound on (non-monotone) interpolants in this fragment. We then apply these results to extend and improve previous results on multilinear proofs (over fields of characteristic 0), as studied in [Ran Raz, Iddo Tzameret, The strength of multilinear proofs. Comput. Complexity (in press)]. Specifically, we show the following: •Proofs operating with depth-3 multilinear formulas polynomially simulate a certain, considerably strong, fragment of resolution over linear equations.•Proofs operating with depth-3 multilinear formulas admit polynomial-size refutations of the pigeonhole principle and Tseitin graph tautologies. The former improve over a previous result that established small multilinear proofs only for the functional pigeonhole principle. The latter are different from previous proofs, and apply to multilinear proofs of Tseitin mod p graph tautologies over any field of characteristic 0. We conclude by connecting resolution over linear equations with extensions of the cutting planes proof system.

Original languageEnglish (US)
Pages (from-to)194-224
Number of pages31
JournalAnnals of Pure and Applied Logic
Volume155
Issue number3
DOIs
StatePublished - Oct 1 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Logic

Keywords

  • Algebraic proof systems
  • Cutting planes
  • Feasible monotone interpolation
  • Multilinear proofs
  • Proof complexity
  • Resolution

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