Hardware and Software: Verification and Testing

Volume 7857 of the series Lecture Notes in Computer Science pp 102-117

Automated Reencoding of Boolean Formulas

  • Norbert MantheyAffiliated withInstitute of Artificial Intelligence, Technische Universität Dresden
  • , Marijn J. H. HeuleAffiliated withDepartment of Computer Science, The University of Texas at AustinInstitute for Formal Models and Verification, Johannes Kepler University
  • , Armin BiereAffiliated withInstitute for Formal Models and Verification, Johannes Kepler University

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We present a novel preprocessing technique to automatically reduce the size of Boolean formulas. This technique, called Bounded Variable Addition (BVA), exchanges clauses for variables. Similar to other preprocessing techniques, BVA greedily lowers the sum of variables and clauses, a rough measure for the hardness to solve a formula. We show that cardinality constraints (CCs) can efficiently be reencoded: from a naive CC encoding, BVA automatically generates a compact encoding, which is smaller than sophisticated encodings. Experimental results show that applying BVA can improve SAT solving performance.