Techniques from combinatorial approximation algorithms yield efficient algorithms for random 2k-SAT

  • Authors:
  • Amin Coja-Oghlan;Andreas Goerdt;André Lanka;Frank Schädlich

  • Affiliations:
  • Humboldt-Universität zu Berlin, Institute für Informatik, Unter den Linden 6, 10099 Berlin, Germany;Technische Universität Chemnitz Fakultät Für Informatik, Straße der Nationen 62, 09107 Chemnitz, Germany;Technische Universität Chemnitz Fakultät Für Informatik, Straße der Nationen 62, 09107 Chemnitz, Germany;Technische Universität Chemnitz Fakultät Für Informatik, Straße der Nationen 62, 09107 Chemnitz, Germany

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2004

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Abstract

We apply techniques from the theory of approximation algorithms to the problem of deciding whether a random k-SAT formula is satisfiable. Let Form n,k,m denote a random k-SAT instance with n variables and m clauses. Using known approximation algorithms for MAX CUT or MIN BISECTION, we show how to certify that Formn,4,m is unsatisfiable efficiently, provided that m ≥ Cn2 for a sufficiently large constant C 0. In addition, we present an algorithm based on the Lovász υ' function that decides within polynomial expected time whether Formn,k,m is satisfiable, provided that k is even and m ≥ C ċ 4knk/2. Finally, we present an algorithm that approximates random MAX 2-SAT on input Formn,2,m within a factor of 1 - O(n/m)1/2 in expected polynomial time. for m ≥ Cn.