A new hybrid procedure that combines genetic operators to existing heuristics is proposed to solve the Quadratic Assignment Problem (QAP). Genetic operators are found to improve the performance of both local search and tabu search. Some guidelines are also given to design good hybrid schemes. These hybrid algorithms are then used to improve on the best… (More)
We discuss the problem of constructing physician schedules in emergency rooms. Starting from practical instances encountered in six different hospitals of the Montreal (Canada) area, we first we propose generic forms for the constraints encountered in this context. We then review several possible solution techniques that can be applied to physician… (More)
A generalized fractional programming problem is specified as a nonlinear program where a nonlinear function defined as the maximum over several ratios of functions is to be minimized on a feasible domain of ~n. The purpose of this paper is to outline basic approaches and basic types of algorithms available to deal with this problem and to review their… (More)
We consider a generalization of a linear fractional program where the maximum of finitel3 many linear ratios is to be minimized subject to linear constraints. For this Min-Max problem a dual in the form of a Max-Min problem is introduced and duality relations are established.