Efficient SAT solving under assumptions

  • Authors:
  • Alexander Nadel;Vadim Ryvchin

  • Affiliations:
  • Intel Corporation, Haifa, Israel;Intel Corporation, Haifa, Israel, Information Systems Engineering, IE, Technion, Haifa, Israel

  • Venue:
  • SAT'12 Proceedings of the 15th international conference on Theory and Applications of Satisfiability Testing
  • Year:
  • 2012

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Abstract

In incremental SAT solving, assumptions are propositions that hold solely for one specific invocation of the solver. Effective propagation of assumptions is vital for ensuring SAT solving efficiency in a variety of applications. We propose algorithms to handle assumptions. In our approach, assumptions are modeled as unit clauses, in contrast to the current state-of-the-art approach that models assumptions as first decision variables. We show that a notable advantage of our approach is that it can make preprocessing algorithms much more effective. However, our initial scheme renders assumption-dependent (or temporary) conflict clauses unusable in subsequent invocations. To resolve the resulting problem of reduced learning power, we introduce an algorithm that transforms such temporary clauses into assumption-independent pervasive clauses. In addition, we show that our approach can be enhanced further when a limited form of look-ahead information is available. We demonstrate that our approach results in a considerable performance boost of the SAT solver on instances generated by a prominent industrial application in hardware validation.