There are, however, cases where nonlinear models of the underlying integer program yield good exact or approximate solution techniques. Although methods such as Lagrangian relaxation and subgradient methods and eigenvalue techniques have been around for quite some while, the nonlinear approach is still a wide open field for research.
In this presentation, the speaker will describe the already mentioned "classical" techniques, but will particularly report about more recent advances where use is made of positive semidefinite forms and relaxations using polynomials of higher degrees.
Martin Grotschel
Konrad-Zuse-Zentrum and Technische Universitat
Berlin, Germany