Stefan Volkwein

An adaptive relaxation-refinement scheme for multi-objective mixed-integer nonconvex optimization

  • Gabriele Eichfelder
  • Moritz Link
  • Stefan Volkwein
  • Leo Warnow
    • Categories (Mixed) Integer Nonlinear Programming, Multi-Criteria Optimization Tags , , , ,

    In this work, we present an algorithm for computing an enclosure for multi-objective mixed-integer nonconvex optimization problems. In contrast to existing solvers for this type of problem, this algorithm is not based on a branch-and-bound scheme but rather relies on a relax-and-refine approach. While this is an established technique in single-objective optimization, several adaptions to … Read more

    Granularity for mixed-integer polynomial optimization problems

  • Carl Eggen
  • Oliver Stein
  • Stefan Volkwein
    • Categories (Mixed) Integer Nonlinear Programming, Semi-definite Programming Tags , , , ,

    Finding good feasible points is crucial in mixed-integer programming. For this purpose we combine a sufficient condition for consistency, called granularity, with the moment-/sos-hierarchy from polynomial optimization. If the mixed-integer problem is granular, we obtain feasible points by solving continuous polynomial problems and rounding their optimal points. The moment-/sos-hierarchy is hereby used to solve those … Read more

    Considering homeowner acceptance of retrofit measures within energy supply network optimization

  • Carl Eggen
  • Moritz Link
  • Stefan Volkwein
    • Categories (Mixed) Integer Nonlinear Programming, Applications - OR and Management Sciences, Multi-Criteria Optimization Tags , , ,

    A key factor towards a low-carbon society is energy efficient heating of private houses. The choice of heating technology as well as the decision for certain energy-efficient house renovations are made mainly by individual homeowners. In contrast, municipal energy network planning heavily depends on and strongly affects these decisions. Further, there are different conflicting objectives … Read more

    Computing an enclosure for multiobjective mixed-integer nonconvex optimization problems using piecewise linear relaxations

  • Moritz Link
  • Stefan Volkwein
    • Categories (Mixed) Integer Nonlinear Programming, Multi-Criteria Optimization, Network Optimization Tags , , , ,

    In this paper, a new method for computing an enclosure of the nondominated set of multiobjective mixed-integer problems without any convexity requirements is presented. In fact, our criterion space method makes use of piecewise linear relaxations in order to bypass the nonconvexity of the original problem. The method chooses adaptively which level of relaxation is … Read more