New methods for calculating $$\alpha $$BB-type underestimators

  • Authors:
  • Anders Skjäl;Tapio Westerlund

  • Affiliations:
  • Center of Excellence in Optimization and Systems Engineering, Åbo Akademi University, Åbo, Finland 20500;Center of Excellence in Optimization and Systems Engineering, Åbo Akademi University, Åbo, Finland 20500

  • Venue:
  • Journal of Global Optimization
  • Year:
  • 2014

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Abstract

Most branch-and-bound algorithms in global optimization depend on convex underestimators to calculate lower bounds of a minimization objective function. The $$\alpha $$BB methodology produces such underestimators for sufficiently smooth functions by analyzing interval Hessian approximations. Several methods to rigorously determine the $$\alpha $$BB parameters have been proposed, varying in tightness and computational complexity. We present new polynomial-time methods and compare their properties to existing approaches. The new methods are based on classical eigenvalue bounds from linear algebra and a more recent result on interval matrices. We show how parameters can be optimized with respect to the average underestimation error, in addition to the maximum error commonly used in $$\alpha $$BB methods. Numerical comparisons are made, based on test functions and a set of randomly generated interval Hessians. The paper shows the relative strengths of the methods, and proves exact results where one method dominates another.