Tight rank lower bounds for the Sherali–Adams proof system

  • Authors:
  • Stefan Dantchev;Barnaby Martin;Mark Rhodes

  • Affiliations:
  • Department of Computer Science, University of Durham, South Road, Durham DH1 3LE, UK;Department of Computer Science, University of Durham, South Road, Durham DH1 3LE, UK;Department of Computer Science, University of Durham, South Road, Durham DH1 3LE, UK

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2009

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Abstract

We consider a proof (more accurately, refutation) system based on the Sherali-Adams (SA) operator associated with integer linear programming. If F is a CNF contradiction that admits a Resolution refutation of width k and size s, then we prove that the SA rank of F is @?k and the SA size of F is @?(k+1)s+1. We establish that the SA rank of both the Pigeonhole Principle PHP"n"-"1^n and the Least Number Principle LNP"n is n-2. Since the SA refutation system rank-simulates the refutation system of Lovasz-Schrijver without semidefinite cuts (LS), we obtain as a corollary linear rank lower bounds for both of these principles in LS.