Polyhedral and algorithmic properties of quantified linear programs

  • Authors:
  • Ulf Lorenz;Alexander Martin;Jan Wolf

  • Affiliations:
  • Institute of Mathematics, Technische Universität Darmstadt, Germany;Institute of Mathematics, Technische Universität Darmstadt, Germany;Institute of Mathematics, Technische Universität Darmstadt, Germany

  • Venue:
  • ESA'10 Proceedings of the 18th annual European conference on Algorithms: Part I
  • Year:
  • 2010

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Abstract

Quantified linear programs (QLPs) are linear programs with variables being either existentially or universally quantified. The integer variant is PSPACE-complete, and the problem is similar to games like chess, where an existential and a universal player have to play a two-person-zero-sum game. At the same time, a QLP with n variables is a variant of a linear program living in Rn, and it has strong similarities with multistage-stochastic programs with variable right-hand side. We show for the continuous case that the union of all winning policies of the existential player forms a polytope in Rn, that its vertices are games of so called extremal strategies, and that these vertices can be encoded with polynomially many bits. The latter allows the conclusion that solving a QLP is in PSPACE. The hardness of the problem stays unknown.