Semidefinite Relaxations of Fractional Programs via Novel Convexification Techniques

  • Authors:

  • Mohit Tawarmalani;Nikolaos V. Sahinidis

  • Affiliations:

  • Department of Mechanical &/ Industrial Engineering, The University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, Illinois 61801, USA/;Department of Chemical Engineering, The University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, Illinois 61801, USA

  • Venue:
  • Journal of Global Optimization
  • Year:
  • 2001

Quantified Score

Hi-index 0.00

Visualization

Abstract

In a recent work, we introduced the concept of convex extensions for lower semi-continuous functions and studied their properties. In this work, we present new techniques for constructing convex and concave envelopes of nonlinear functions using the theory of convex extensions. In particular, we develop the convex envelope and concave envelope of z=x/y over a hypercube. We show that the convex envelope is strictly tighter than previously known convex underestimators of x/y. We then propose a new relaxation technique for fractional programs which includes the derived envelopes. The resulting relaxation is shown to be a semidefinite program. Finally, we derive the convex envelope for a class of functions of the type f(x,y) over a hypercube under the assumption that f is concave in x and convex in y.