This article develops several strategies for the parallelization of the metaheuristic called scatter search, which is a population-based method that constructs solutions by combining others. Three types of parallelization have been proposed to achieve either an increase of efficiency or an increase of exploration. The procedures have been coded in C using OpenMP and compared in a shared memory ...

In this article, we elaborate on a budget constrained extension of the r -interdiction median problem with fortification (RIMF). The objective in the RIMF is to find the optimal allocation of protection resources to a given service system consisting of p facilities so that the disruptive effects of r possible attacks to the system are minimized. The defender of the system needs to fortify q fac...

Given a set of clients and a set of potential sites for facilities, the p-median problem consists of opening a set of p sites and assigning each client to the closest open facility to it. It can be viewed as a variation of the uncapacitated facility location problem. We propose a new formulation of this problem by a mixed integer linear problem. We show that this formulation, while it has the s...

The p-median offers an alternative to centroid-based clustering algorithms for identifying unobserved categories. However, existing p-median formulations typically require data aggregation into a single proximity matrix, resulting in masked respondent heterogeneity. A proposed three-way formulation of the p-median problem explicitly considers heterogeneity by identifying groups of individual re...

Authors investigate the p-median location problem on networks and propose a heuristic algorithm which is based on the probability changing method (a special case of the genetic algorithm) for an approximate solution to the problem. The ideas of the algorithm are proposed under the assumption that, in the largescale networks with comparatively small edge lengths, the p-median problem has feature...

During evolution, chromosomal rearrangements, such as reciprocal translocation, transposition and inversion, disrupt gene content and gene order on chromosomes. We discuss algorithmic and statistical approaches to the analysis of comparative genomic data. In a phylogenetic context, a combined approach is suggested, leading to the median problem for breakpoints. We solve this problem first for t...

The capacitated p-median problem (CPMP) seeks to obtain the optimal location of p medians considering distances and capacities for the services to be given by each median. This paper presents an efficient hybrid metaheuristic algorithm by combining a proposed cutting-plane neighborhood structure and a tabu search metaheuristic for the CPMP. In the proposed neighborhood structure to move from th...

Abstract Location-Routing problems involve locating a number of facilities among candidate sites and establishing delivery routes to a set of users in such a way that the total system cost is minimized. A special case of these problems is Hamiltonian p Median Problem (HpMP). In attempting to solve this problem, numerous mathematical formulations have been proposed. Most of them have in common t...

This paper advocates the use of the bionomic algorithm, a recently proposed metaheuristic technique, as an effective method to solve capacitated p-median problems (CPMP). Bionomic algorithms already proved to be an effective framework for finding good solutions to combinatorial optimization problems, when good local optimization algorithms are available. The paper also presents an effective loc...

In this paper three recurrent neural network algorithms are proposed for the p-median problem according to different techniques. The competitive recurrent neural network, based on two types of decision variables (location variables and allocation variables), consists of a single layer of 2Np process units (neurons), where N is the number of demand points or customers and p is the number of faci...