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 proposes a bi-objective reliable supply chain network design that immunizes the network against different sources of uncertainties. In this regard, scenario based stochastic programming method is applied to model different disruption scenarios affecting accurate performance of network stages. Also, reliable and unreliable facilities are suggested for lessening vulnerability of networ...

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, ...

We propose a maximal covering location problem for helicopter emergency medical service system. In the system, the transportation time of each patient to a hospital depends on both locations of helipads for helicopters to land and take off and hospitals for deploying helicopters. The aim of this paper is to provide an optimal location strategy of both the helipads and the hospitals so as to max...

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...

Clear cell renal cell carcinoma (ccRCC) is the most common solid lesion within kidneys, and its prognostic is influenced by the progression covering a complex network of gene interactions. In our study, a weighted gene co‑expression network was constructed to identify gene modules associated with the progression of ccRCC (n=35). In the significant module (R2 = -0.53), a total of 13 network hub ...

Let X be a compact Riemann surface of genus ≥ 2 of constant negative curvature −1. An extremal disk is an embedded (resp. covering) disk of maximal (resp. minimal) radius. A surface containing an extremal disk is an extremal surface. This paper gives formulas enumerating extremal surfaces of genus ≥ 4 up to isometry. We show also that the isometry group of an extremal surface is always cyclic o...