Computational complexity of quantified Boolean formulas with fixed maximal deficiency

  • Authors:
  • Hans Kleine Büning;Xishun Zhao

  • Affiliations:
  • Department of Computer Science, Universität Paderborn, 33095 Paderborn, Germany;Institute of Logic and Cognition, Sun Yat-sen University, 510275 Guangzhou, PR China

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2008

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Abstract

The paper investigates the computational complexity of quantified Boolean formulas with fixed maximal deficiency. The satisfiability problem for quantified Boolean formulas with maximal deficiency 1 is shown to be solvable in polynomial time. For k=1, it is shown that true formulas with fixed maximal deficiency k have models in which all Boolean functions can be represented as CNF formulas over at most 2^4^k^/^3 universal variables. As a consequence, the satisfiability problem for QCNF formulas with fixed maximal deficiency is in NP and for fixed deficiency the minimal falsity problem is in D^P. For two subclasses of quantified Boolean formulas with PSPACE-complete evaluation problem, QEHORN and QE2-CNF , we show that for fixed deficiency the minimal falsity problem can be decided in polynomial time.