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Efficient CNF Simplification Based on Binary Implication Graphs

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Part of the Lecture Notes in Computer Science book series (LNTCS,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.

The 1st author is financially supported by Dutch Organization for Scientific Research (grant 617.023.611), the 2nd author by Academy of Finland (grant 132812) and the 1st and 3rd author are supported by the Austrian Science Foundation (FWF) NFN Grant S11408-N23 (RiSE).

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Heule, M.J.H., Järvisalo, M., Biere, A. (2011). Efficient CNF Simplification Based on Binary Implication Graphs. In: Sakallah, K.A., Simon, L. (eds) Theory and Applications of Satisfiability Testing - SAT 2011. SAT 2011. Lecture Notes in Computer Science, vol 6695. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-21581-0_17

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  • DOI: https://doi.org/10.1007/978-3-642-21581-0_17

  • Publisher Name: Springer, Berlin, Heidelberg

  • Print ISBN: 978-3-642-21580-3

  • Online ISBN: 978-3-642-21581-0

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