A CNF formula hierarchy over the hypercube

  • Authors:
  • Stefan Porschen

  • Affiliations:
  • Institut für Informatik, Universität zu Köln, Köln, Germany

  • Venue:
  • AI'07 Proceedings of the 20th Australian joint conference on Advances in artificial intelligence
  • Year:
  • 2007

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Abstract

We study the first level of a conjunctive normal form (CNF) formula hierarchy with respect to the propositional satisfiability problem (SAT). This hierarchy is defined over a base formula that we call a hypercube (formula). Such a hypercube simply consists of all 2n possible n-clauses over a given set of n Boolean variables. The first level of the hierarchy are 1-hyperjoins, meaning that arbitrary hypercubes are joined together via taking from each arbitrary many clauses for joining, i.e., set-union, such that each chosen clause occurs in at most one new clause of the 1-hyperjoin. We prove that arbitrary 1-hyperjoins can efficiently be recognized and solved w.r.t. SAT. To that end we introduce a simple closure concept on the set of the propositional variables of a formula.