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Transportation problems are essential in commercial logistics and have been widely studied in the litera- ture during the last decades. Many of them consist in designing routes for vehicles to move commodities between locations. This article approaches a pickup-and-delivery single-vehicle routing problem where there is susceptibility to uncertainty in customer requests. The probability distributions of the requests are assumed to be known, and the objective is to design an a priori route with minimum expected length. The problem has already been approached in the literature, but through a heuristic method. This article proposes the first exact approach to the problem. Two mathematical formulations are proposed: one is a compact model (i.e. defined by a polynomial number of variables and constraints); the other one contains an exponential number of inequalities and is solved within a branch-and-cut framework. Computational results show the upsides as well as the breakdowns of both formulations., Spanish Government (MINECO/FEDER), Government of Madrid, Depto. de Economía Financiera y Actuarial y Estadística, Fac. de Ciencias Económicas y Empresariales, TRUE, pub

This paper approaches a pickup and delivery problem with multiple vehicles in which LIFO conditions are imposed when performing loading and unloading operations and the route durations cannot exceed a given limit. We propose two mixed integer formulations of this problem and a heuristic procedure that uses tabu search in a multi-start framework. The first formulation is a compact one, that is, the number of variables and constraints is polynomial in the number of requests, while the second one contains an exponential number of constraints and is used as the basis of a branch-and-cut algorithm. The performances of the proposed solution methods are evaluated through an extensive computational study using instances of different types that were created by adapting existing benchmark instances. The proposed exact methods are able to optimally solve instances with up to 60 nodes., Generalitat Valenciana, Government of Spain, RDEF funds, Fundacion Seneca, FEDER, Depto. de Estadística e Investigación Operativa, Fac. de Ciencias Matemáticas, TRUE, pub

El desarrollo del proyecto gira en torno a un circuito integrado, el UC3906, de Texas, que es un circuito integrado de propósito específico y ha sido diseñado para la carga de baterías. Nos proporciona prestaciones muy interesantes con un mínimo número de componentes externos

El desarrollo del proyecto gira en torno a un circuito integrado, el UC3906, de Texas, que es un circuito integrado de propósito específico y ha sido diseñado para la carga de baterías. Nos proporciona prestaciones muy interesantes con un mínimo número de componentes externos

El desarrollo del proyecto gira en torno a un circuito integrado, el UC3906, de Texas, que es un circuito integrado de propósito específico y ha sido diseñado para la carga de baterías. Nos proporciona prestaciones muy interesantes con un mínimo número de componentes externos

[EN] In this paper we deal with the min¿max version of the windy rural postman problem with K vehicles. For this problem, in which the objective is to minimize the length of the longest tour in order to find a set of balanced tours for the vehicles, we present here a metaheuristic that produces very good feasible solutions in reasonable computing times. It is based on the combination of a multi-start procedure with an Iterated Local Search. Extensive computational results on a large set of instances with up to 50 vertices, 184 edges and 5 vehicles are presented. The results are very good, the average gaps with respect to a known lower bound are less than 0.40% for instances with 2 or 3 vehicles and up to 1.60% when 4 or 5 vehicles are considered.

[EN] In this paper we deal with the min¿max version of the windy rural postman problem with K vehicles. For this problem, in which the objective is to minimize the length of the longest tour in order to find a set of balanced tours for the vehicles, we present here a metaheuristic that produces very good feasible solutions in reasonable computing times. It is based on the combination of a multi-start procedure with an Iterated Local Search. Extensive computational results on a large set of instances with up to 50 vertices, 184 edges and 5 vehicles are presented. The results are very good, the average gaps with respect to a known lower bound are less than 0.40% for instances with 2 or 3 vehicles and up to 1.60% when 4 or 5 vehicles are considered.

In this paper we consider the Capacitated Arc Routing Problem, in which a fleet of K vehicles, all of them based on a specific vertex (the depot) and with a known capacity Q, must service a subset of the edges of the graph, with minimum total cost and such that the load assigned to each vehicle does not exceed its capacity. A heuristic algorithm for this problem is proposed consisting of: the selection of K centers, the construction of K connected graphs with associated loads not exceeding the vehicle capacities, the resolution of a General Assignment Problem, if necessary, to get a complete assignment of edges to vehicles and finally the construction of the routes by solving heuristically a Rural Postman Problem for each vehicle. Computational results on graphs up to 50 vertices and 97 edges are included. On average, the feasible solution is within 6,4% of the best known lower bound.

El objetivo de este artículo es ofrecer una visión general de la situación actual de la investigación en Problemas de Rutas por Arcos, que consisten, básicamente, en encontrar rutas óptimas que atraviesen las aristas o/y arcos de un grafo dado. Se analizan, entre otros, el Problema del Cartero Chino (definido sobre grafos dirigidos, no dirigidos o mixtos), el Problema del Cartero Rural (dirigido y no dirigido), así como el problema de los m-Carteros con alguna de sus variantes. En todos los casos se ha intentado ofrecer los resultados existentes relativos a: complejidad de los problemas, algoritmos exactos desarrollados, así como métodos heurísticos con el correspondiente análisis del peor caso., The purpose of this paper is to survey the state of knowledge in the area of Arc Routing Problems. These problems consist, roughly speaking, of finding routes that traverse, partially or totally, the edges (or/and arcs) of a given graph, in an optimal way. Among others, we analize the Chinese Postman Problem (defined on directed, nondirected and mixed graphs), the Rural Postman Problem (directed and nondirected cases) as well as the m-Postmen Problem in Borne of its versions. In all cases, we present the existing results, as far as we know, concerning the complexity of the problems, the exact algorithms developed as well as the heuristic procedures with their corresponding worst case analysis.

Ded.: "A la Sociedad coral Pacheco de Mondoñedo", Nº 7710 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, T(2)BarB, Fecha de publicación tomada de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997

Nº 5551 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, T(2)BarB, Fecha de publicación tomada de La edición musical española hasta 1936, 1995

Portada litografiada firmada por Enrique Abad y Gil, Nº 4991 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, Fecha de publicación basada en La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997

Portada ilustrada firmada por Enrique Abad y Gil, Nº 5024 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, Voz y piano, op. 509, Fecha de publicación basada en La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997

Fecha de publicación tomada de La edición musical española hasta 1936, 1995

Ded.: "A la Sociedad coral Pacheco de Mondoñedo", Nº 7710 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, T(2)BarB, Fecha de publicación tomada de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997

Nº 5551 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, T(2)BarB, Fecha de publicación tomada de La edición musical española hasta 1936, 1995

Portada litografiada firmada por Enrique Abad y Gil, Nº 4991 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, Fecha de publicación basada en La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997

Portada ilustrada firmada por Enrique Abad y Gil, Nº 5024 de La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997, Voz y piano, op. 509, Fecha de publicación basada en La música en el Boletín de la Propiedad Intelectual, Biblioteca Nacional, 1997

Fecha de publicación tomada de La edición musical española hasta 1936, 1995

Datos de publicación tomados de La música en el Boletín de la Propiedad Intelectual, 1997