Combinatorial proof that subprojective constraint satisfaction problems are NP-complete

  • Authors:
  • Jaroslav Nešetřil;Mark Siggers

  • Affiliations:
  • Department of Applied Mathematics and Institute for Theoretical Computer Science (ITI), Charles University, Praha, Czech Republic;Department of Applied Mathematics and Institute for Theoretical Computer Science (ITI), Charles University, Praha, Czech Republic

  • Venue:
  • MFCS'07 Proceedings of the 32nd international conference on Mathematical Foundations of Computer Science
  • Year:
  • 2007

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Abstract

We introduce a new general polynomial-time constructionthe fibre construction- which reduces any constraint satisfaction problem CSP(H) to the constraint satisfaction problem CSP(P), where P is any subprojective relational structure. As a consequence we get a new proof (not using universal algebra) that CSP(P) is NP-complete for any subprojective (and thus also projective) relational structure. This provides a starting point for a new combinatorial approach to the NP-completeness part of the conjectured Dichotomy Classification of CSPs, which was previously obtained by algebraic methods. This approach is flexible enough to yield NP-completeness of coloring problems with large girth and bounded degree restrictions.