The Constructive Genetic Algorithm (CGA) was proposed by Lorena and Furtado [6], as an alternative to the traditional GAs approach. Particularly the CGA directly evaluates schemata, works with a dynamic population size, performs mutation in complete structures, and uses heuristics in schemata and/or structure representation. The schemata are evaluated and can be added to the population if they ...

Covering problems are well studied in the Operations Research literature under the assumption that both the set of users and the set of potential facilities are finite. In this paper we address the following variant, which leads to a Mixed Integer Nonlinear Program (MINLP): locations of p facilities are sought along the edges of a network so that the expected demand covered is maximized, where ...

This paper concerns a class of maximum covering location problems in networks in uncertain environments. It is assumed that: (a) relative weights of demand nodes are either deterministic or imprecise, described by linguistic expressions, (b) potential facility site locations are limited to network nodes. The concept of coverage is extended to include a degree of node coverage which means that t...

A 2-level hierarchical extension of the maximal covering location problem is considered and an e0ective method for its solution developed. A combined Lagrangean–surrogate (L–S) relaxation is de6ned which reduces to a 0–1 knapsack problem. Tests were carried out using a subgradient-based heuristic incorporating the L–S relaxation, with the resulting knapsack problems being solved both with and w...

This paper proposes a cluster partitioning technique to calculate improved upper bounds to the optimal solution of maximal covering location problems. Given a covering distance, a graph is built considering as vertices the potential facility locations, and with an edge connecting each pair of facilities that attend a same client. Coupling constraints, corresponding to some edges of this graph, ...

In this paper we develop a network location model that combines the characteristics of ordered median and gradual cover models resulting in the Ordered Gradual Covering Location Problem (OGCLP). The Gradual Cover Location Problem (GCLP) was specifically designed to extend the basic cover objective to capture sensitivity with respect to absolute travel distance. Ordered Median Location problems ...

This article presents a column generation algorithm to calculate new improved lower bounds to the solution of maximal covering location problems formulated as a p-median problem. This reformulation leads to instances that are difficult for column generation methods. The traditional column generation method is compared with the new approach, where the reduced cost criterion used at the column se...

This paper studies capacitated single-allocation hub covering location problem with fuzzy cover radius and travel time. Objective of hub covering problem is to find the minimum number of hubs considering the maximum allowable travel time. Computational results show that due to uncertainty, number of hubs and the allocation of non-hub nodes to hub nodes are changed. This paper proposes heuristic...

This study introduces a green location, routing and inventory problem with customer satisfaction, backup distribution centers and risk of routes in the form of a non-linear mixed integer programming model. In this regard, time window is considered to increase the customer satisfaction of the model and transportation risks is taken into account for the reliability of the system. In addition, dif...