Efficient Recognition of Random Unsatisfiable k-SAT Instances by Spectral Methods

  • Authors:
  • Andreas Goerdt;Michael Krivelevich

  • Affiliations:
  • -;-

  • Venue:
  • STACS '01 Proceedings of the 18th Annual Symposium on Theoretical Aspects of Computer Science
  • Year:
  • 2001

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Abstract

It is known that random k-SAT instances with at least cn clauses where c = ck is a suitable constant are unsatisfiable (with high probability). We consider the problem to certify efficiently the unsatisfiability of such formulas. A result of Beame et al. shows that k-SAT instances with at least nk-1/ log n clauses can be certified unsatisfiable in polynomial time. We employ spectral methods to improve on this: We present a polynomial time algorithm which certifies random k-SAT instances for k even with at least 2k ċ (k/2)7 ċ (ln n)7 ċ nk/2 = n(k/2)+o(1) clauses as unsatisfiable (with high probability).