Some Results on Random Unsatisfiable k-Sat Instances and Approximation Algorithms Applied to Random Structures

  • Authors:
  • Andreas Goerdt;Tomasz Jurdzinski

  • Affiliations:
  • -;-

  • Venue:
  • MFCS '02 Proceedings of the 27th International Symposium on Mathematical Foundations of Computer Science
  • Year:
  • 2002

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Abstract

It is known that random k-Sat instances with at least cn random clauses where c = ck is a suitable constant are unsatisfiable with high probability. These results are obtained by estimating the expected number of satisfying assignments and thus do not provide us with an efficient algorithm. Concerning efficient algorithms it is only known that formulas with n驴 驴nk/2 clauses with k literals over n underlying variables can be efficiently certified as unsatisfiable. The present paper is the result of trying to lower the preceding bound.We obtain better bounds for some specialized satisfiability problems.