Hybrid heuristics for the permutation flow shop problem

The Flow Shop Problem (FSP) is known to be NP-hard when more than three machines are considered. Thus, for non-trivial size problem instances, heuristics are needed to find good orderings. We consider the permutation case of this problem. For this case, denoted by F|prmu|Cmax, the sequence of jobs has to remain the same at each … Read more

A continuous GRASP to determine the relationship between drugs and adverse reactions

Adverse drug reactions (ADRs) are estimated to be one of the leading causes of death. Many national and international agencies have set up databases of ADR reports for the express purpose of determining the relationship between drugs and adverse reactions that they cause. We formulate the drug-reaction relationship problem as a continuous optimization problem and … Read more

Global optimization by continuous GRASP

We introduce a novel global optimization method called Continuous GRASP (C-GRASP) which extends Feo and Resende’s greedy randomized adaptive search procedure (GRASP) from the domain of discrete optimization to that of continuous global optimization. This stochastic local search method is simple to implement, is widely applicable, and does not make use of derivative information, thus … Read more

A novel integer programming formulation for the K-SONET ring assignment problem

We consider the problem of interconnecting a set of customer sites using SONET rings of equal capacity, which can be defined as follows: Given an undirected graph G=(V,E) with nonnegative edge weight d(u,v), (u,v) in E, and two integers K and B, find a partition of the nodes of G into K subsets so that … Read more

GRASP for nonlinear optimization

We propose a Greedy Randomized Adaptive Search Procedure (GRASP) for solving continuous global optimization problems subject to box constraints. The method was tested on benchmark functions and the computational results show that our approach was able to find, in a few seconds, optimal solutions for all tested functions despite not using any gradient information about … Read more