Valid Linear Programming Bounds for Exact Mixed-Integer Programming

  • Authors:
  • Daniel E. Steffy;Kati Wolter

  • Affiliations:
  • Department of Mathematics and Statistics, Oakland University, Rochester, Michigan 48309;Department of Optimization, Zuse Institute Berlin, 14195 Berlin, Germany

  • Venue:
  • INFORMS Journal on Computing
  • Year:
  • 2013

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Abstract

Fast computation of valid linear programming LP bounds serves as an important subroutine for solving mixed-integer programming problems exactly. We introduce a new method for computing valid LP bounds designed for this application. The algorithm corrects approximate LP dual solutions to be exactly feasible, giving a valid bound. Solutions are repaired by performing a projection and a shift to ensure all constraints are satisfied; bound computations are accelerated by reusing structural information through the branch-and-bound tree. We demonstrate this method to be widely applicable and faster than solving a sequence of exact LPs. Several variations of the algorithm are described and computationally evaluated in an exact branch-and-bound algorithm within the mixed-integer programming framework SCIP Solving Constraint Integer Programming.