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Efficient CNF Simplification Based on Binary Implication Graphs

  • Marijn J. H. Heule
  • Matti Järvisalo
  • Armin Biere
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6695)

Abstract

This paper develops techniques for efficiently detecting redundancies in CNF formulas. We introduce the concept of hidden literals, resulting in the novel technique of hidden literal elimination. We develop a practical simplification algorithm that enables “Unhiding” various redundancies in a unified framework. Based on time stamping literals in the binary implication graph, the algorithm applies various binary clause based simplifications, including techniques that, when run repeatedly until fixpoint, can be too costly. Unhiding can also be applied during search, taking learnt clauses into account. We show that Unhiding gives performance improvements on real-world SAT competition benchmarks.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Marijn J. H. Heule
    • 1
  • Matti Järvisalo
    • 2
  • Armin Biere
    • 3
  1. 1.Department of Software TechnologyDelft University of TechnologyThe Netherlands
  2. 2.Department of Computer ScienceUniversity of HelsinkiFinland
  3. 3.Institute for Formal Models and VerificationJohannes Kepler University LinzAustria

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