The phase transition in random horn satisfiability and its algorithmic implications

  • Authors:
  • Gabriel Istrate

  • Affiliations:
  • D-2 Division, Los Alamos National Laboratory, Mail Stop M 997, Los Alamos, NM

  • Venue:
  • Random Structures & Algorithms
  • Year:
  • 2002

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Abstract

Let c 0 be a constant, and Φ be a random Horn formula with n variables and m = c . 2n clauses, chosen uniformly at random (with repetition) from the set of all nonempty Horn clauses in the given variables. By analyzing PUR, a natural implementation of positive unit resolution, we show that limn→∞ Pr(Φ is satisfiable) = 1 - F(e-c), where F(x) = (1 - x)(1 - x2)(1 - x4) (1 - x8) .... Our method also yields as a byproduct an average-case analysis of this algorithm.