Blocked Literals Are Universal

  • Marijn  J. H. HeuleEmail author
  • Martina Seidl
  • Armin Biere
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9058)


We recently introduced a new proof system for Quantified Boolean Formulas (QBF), called QRAT, that opened up a variety of new preprocessing techniques. This paper presents a concept that follows from the QRAT proof system: blocked literals. Blocked literals are redundant universal literals that can be removed or added to clauses. We show that blocked literal elimination (BLE) and blocked literal addition are not confluent. We implemented BLE in the state-of-the-art preprocessor bloqqer. Our experimental results illustrate that the BLE extension improves solver performance on the 2014 QBF evaluation benchmarks.


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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Marijn  J. H. Heule
    • 1
    Email author
  • Martina Seidl
    • 2
  • Armin Biere
    • 2
  1. 1.Department of Computer ScienceThe University of Texas at AustinAustinUSA
  2. 2.Institute for Formal Models and VerificationJKU LinzLinzAustria

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