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Publications (58)
Tourism generates huge amounts of waste. It has been estimated that about half of the waste generated by hotels is food and garden bio-waste. This bio-waste can be used to make compost and pellets. In turn, pellets can be used as an absorbent material in composters and as an energy source. In this paper, we consider the problem of locating composti...
We consider a tourist trip design problem with time windows and recommended occupancy levels at the points of interest. A 3-objective optimization model is formulated where the objectives are to maximize the total score and minimize total over occupancy and time gap. The multiobjective optimization problem is modeled as a mixed integer linear mathe...
The leader-follower problem is a sequential decision problem where, in a market initially without service centers, a firm, the leader, opens its centers and another competing firm, the follower, will enter later the market opening its centers. The leader chooses the locations taking into account that the follower will enter the market opening its c...
In the leader-follower, (r|p)-centroid or Stackelberg location problem, two players sequentially enter the market and compete to provide goods or services. This paper considers this competitive facility location problem in a discrete space. To solve it, the linear programming formulations for the leader and the follower are integrated into an algor...
Many structural relationships should be taken into account in any reasonable adjustment
and updating process. These structural relationships are mainly represented by ratios of different types, such as technical coefficients or the proportion of the cell value in relation to its row or column total. We believe that in many cases (either because of...
We consider the leader-follower problem in a discrete space. We apply an algorithm which integrates the linear programming formulation of the problems for the leader and the follower and, in an iterative process, finds a solution by solving a sequence of these linear problems. We propose a matheuristic procedure where the problem of the leader is s...
In this work we present an adjustment/updating procedure of Social Accounting Matrices (SAM) using multiobjective optimization techniques. The usual setting concentrates the adjustment effort in either the column or row coefficients of the SAM. The normal tendency consists in using the column coefficients because they better reflect the technical c...
The (r|p)-centroid problem or leader-follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulatio...
A bibliometric analysis to evaluate global scientific production in the
subject category of Operations Research and Management Science (OR/MS) from
2001 to 2012 was applied. Data was based on the Web of Science (Science
Citation Index) database compiled by Thomson Reuters. The results showed that
the OR/MS research has significantly increased over...
This article deals with a network competitive localization problem in which a firm seeks to determine the location of a new facility, which competes with all the facilities operating in the market, both belonging to the same firm and to the competing firms. In this context, two frequently conflicting objectives are involved: maximization of the tot...
The journal impact factor is not comparable among fields of science and
social science because of systematic differences in publication and citation
behaviour across disciplines. In this work, a source normalization of the
journal impact factor is proposed. We use the aggregate impact factor of the
citing journals as a measure of the citation poten...
In this paper, the problem of determining the location and quality of new facilities in a network market is analyzed. Customers make their choice according to an attraction function, which is directly proportional to the facility quality level and decreasing with respect to the distance between customers and facilities. In order to solve the locati...
Competitive location models and GIS are combined to build decision-aid tools in a franchise distribution system when a single facility has to be located in a continuous space. Several objectives are involved, which are sometimes in conflict, and a certain equilibrium among these objectives is desirable. Competitive location models are used to repre...
We consider the (r|Xp)−medianoid problem in networks. Goods are
assumed to be essential and the only decision criterion is the travel
distance. The portion of demand captured by the competitors is modelled
by a general capture function which includes the binary, partially binary
and proportional customer choice rules as specific cases. We prove tha...
The (r|p)-centroid problem is a competitive location problem that consists of determining optimal strategies for two competing firms, the leader and the follower, which make decisions sequentially. We propose a particle swarm optimization procedure with two swarms to solve the discrete (r|p)-centroid problem. The proposed algorithm considers a swar...
In this paper a competitive network location problem is treated. We consider a proportional
choice rule derived from the Huff model, where facility location and other attributes, such as
size and service quality, are considered. This problem is solved using Geographical
Information Systems in a raster environment. Later, the obtained layer with...
En este trabajo consideramos un problema de localización donde dos empresas entran secuencialmente en un mercado, compitiendo por captar clientes distribuidos en un conjunto finito de puntos, a los que ofrecen un producto o servicio. La demanda existente se reparte entre las empresas competidoras atendiendo a la proximidad entre clientes y centros...
The leader—follower location problem consists of determining an optimal strategy for two competing firms which make decisions
sequentially. The leader optimisation problem is to minimise the maximum market share of the follower. The objective of the
follower problem is to maximise its market share. We describe linear programming formulations for bo...
In this paper, we have used Geographical Information Systems (GIS) to solve the planar Huff problem considering different demand distributions and forbidden regions. Most of the papers connected with the competitive location problems consider that the demand is aggregated in a finite set of points. In other few cases, the models suppose that the de...
In this paper, we have used a GIS based model to solve the planar Huff problem. Most of the papers connected with the competitive location problems consider that the demand is aggregated in a finite set of points. In this case, we have considered that the demand is distributed along the plane according to a surface model of population, that is, a r...
This paper deals with the competitive location problems using fuzzy sets. The basic notions on fuzzy optimization and linear programming using fuzzy sets are briefly reviewed. The standard leader-follower location problem and its linear mathematical programming formulation are described. The works appeared in the literature concerning the use of fu...
Resumen En este trabajo se elabora una comparativa de las instituciones (universidades, centros y escuelas de negocio) españolas de investigación en el área de Economía y Empresa, a partir de los artículos publicados (producción) y las citas recibidas (impacto) en el período 1994-2006. Se muestra la información para las 49 instituciones (41 univers...
This paper presents a location–price equilibrium problem on a tree. A sufficient condition for having a Nash equilibrium in a spatial competition model that incorporates price, transport, and externality costs is given. This condition implies both competitors are located at the same point, a vertex that is the unique median of the tree. However, th...
Competitive location problems consist of determining optimal strategies for competing firms which make location decisions. The standard problem is the leader-follower location problem which consists of determining optimal strategies for two competing firms, the leader and the follower, which make decisions sequentially. The follower has the objecti...
In this paper a competitive network location problem is treated. We consider a proportional choice rule derived from the Huff model, where facility location and other attributes, such as size and service quality, are considered. The model we propose incorporates additional geographical information such as the land use the proximity to main roads, t...
In this paper a covering model for locating facilities with time-dependent demand is introduced. Not only the facility locations, but also the instants at which such facilities become operative, are considered as decision variables in order to determine the maximal-profit decision. Expressed as a mixed nonlinear integer program, structural properti...
In this research note, the follower location problem where the customers' choice is based on an attraction function is analysed. The attraction function depends on both the distance between customers and facilities, and the characteristics (quality) of the facilities. Customers at each node impose a minimum level of attraction in order to patronise...
This paper summarizes some results for the leader–follower location model on networks in several scenarios. Discretization results are considered and differences derived from the inelastic and elastic demand assumptions, as well as from the customer’s choice rule, are emphasized. Finally, some issues for future lines of investigation are suggested....
This paper presents a location-price equilibrium problem on a tree. Nash equilibrium conditions are presented for a spatial competition model that incorporates price, transport and externality costs. The presented result. describes a sufficient condition under which the Nash equilibria on locations and prices are guaranteed. Moreover, the Nash equi...
Most of the competitive location problems assume essential services, which means that the total demand is allocated to the facilities operating in the market. This is a reasonable assumption for first order goods but not for services such as restaurants or cinemas which can be unused by consumers if, for example, the travel distance is large or the...
Consider a two-stage non-cooperative Cournot game with location choice involving
two firms. There aren spatially separated markets located at the vertices of a network. Each
firm, first selects the location of a facility and then selects the quantities to supply to the
markets in order to maximize its profit. Non-zero conjectural variation at th...
We consider a two-stage non-cooperative Bertrand game with location choice involving r firms. There are n spatially separated markets located at the vertices of a network. Each firm first selects the location of a facility and then selects the delivered price in the markets in order to maximise its profit. The article extends the duopolistic model...
We investigate the (r∣Xp)-medianoid problem for networks. This is a competitive location problem that consists of determining the locations of r facilities belonging to a firm in order to maximize its market share in a space where a competitor is already operating with p facilities. We consider six scenarios resulting from the combination of three...
Consider a two-stage non-cooperative Cournot game with location choice involving r firms. There are n spatially separated markets located at the vertices of a network. Each firm, first selects the location of a facility and then selects the quantities to supply to the markets in order to maximize its profit. Non-zero conjectural variation at the se...
In this paper an extension of the (r|X
p
)-medianoid on networks introduced by Hakimi (1983) is studied. In this extension the customer considers not only the distance but some characteristics of the facilities such as store size, quality of service and parking space. A new firm wants to establishr new facilities which have to compete with thep fac...
We believe that any adjustment and updating process (AUP) should try to minimize the relative deviation of the new coefficients from the intial ones in a homogeneus way. This homogenity would mean that the magnitude of this relative deviation is similar among the elements of each row or column, therefor avoiding the concentration of the changes in...
We investigate the (r|Xp)-medianoid problem for networks. This is a competitive location problem that consists of determining the locations of "r" facilities belonging to a firm in order to maximize its market share in a space where a competitor is already operating with "p" facilities. We consider six scenarios resulting from the combination of th...
We believe that any adjustment and updating process (AUP) should try to minimize the relative deviation of the new coefficients from the initial ones in a homogeneous way. This homogeneity would mean that the magnitude of this relative deviation is similar among the elements of each row or column, therefore avoiding the concentration of the changes...
A spatial competition model involving decisions made by consumers and firms is proposed. A regulating agent assigns the demand, taking into account the price, transport and externality cost, and minimizing the joint consumer cost to obtain a Pareto optimal allocation. Assuming the Pareto optimal allocation, firms fix prices in order to maximize the...
La elasticidad de la demanda condiciona la política de precios. Eneste trabajo se analizan dos escenarios diferentes, el de demanda totalmente inelástica al precio y el de demanda lineal, como caso particular de demanda elástica. En elproblema estudiado, dos empresas deben decidir sus ubicaciones en una red y los precios fijados en un conjunto de m...
Demand elasticity affect to price policy. In this work, two different sceneries are analyzed: inelastic demand and linear demand as a particular case of elastic demand. In this prolem two firms decide locations on a network and prices in a set of spatial separated markets. The competence process is modeled as a two-stage game, locations are decided...
En este trabajo se plantea un problema relacionado con la recogida, transporte y tratamiento de residuos. Se consideran centros generadores de residuos y centros de tratamiento, y se contempla la instalación de nuevas plantas de tratamiento en ciertas localizaciones seleccionadas en un conjunto de lugares candidatos. Para escoger estas localizacion...
En este trabajo se describe la experiencia de cambio de examen en la asignatura de Matemáticas I (del primer cuatrimestre del primer curso) de las titulaciones Licenciatura en Economía, Licenciatura en Administración. y Dirección. de Empresas y Diplomatura en Ciencias Empresariales, llevada a cabo durante el presente curso académico. Esencialmente,...
El software matemático se ha venido empleando desde hace varios años como un asistente más en la docencia de ciertas titulaciones con buenos resultados. Las ventajas de su utilización son muchas. En este trabajo se muestra una práctica de optimización matemática con ayuda de LINGO. Se proponen dos problemas, uno lineal y otro no lineal, relacionado...
En gran parte de los modelos de competencia espacial se asume que la elección de los usuarios está basada en el coste final del servicio (precio del producto más coste de transporte) y que son exclusivamente las empresas las que presentan un comportamiento estratégico en la toma de decisiones sobre la ubicación y el precio. Sin embargo, es bastante...
Most of spatial competition models assume firm decisions exclusively. In these models, customers choose the facility minimizing price plus transport cost. However, in markets with externalities, customer decisions are taken in relation to the behaviour of the rest of customers. In this paper, externality costs are considered, and customer decisions...
Se estudia un problema de localización competitiva en redes. Una firma quiere establecer r centros de servicio en un mercado donde otras firmas competidoras ya disponen de p centros. Los centros pueden estar ubicados en cualquier punto de la red y la demanda se concentra en los nodos. La cantidad de demanda de un nodo que es captada por un centro d...
En gran parte de los modelos de competencia espacial se asume que la elección de los usuarios está basada en el coste final del servicio (precio más coste de transporte) y que son exclusivamente las empresas las que presentan un comportamiento estratégico. Sin embargo, es bastante habitual que los usuarios también actúen estratégicamente con el fin...
En gran parte de los modelos de competencia espacial se asume que la elección de los usuarios está basada en el coste final del servicio (precio más coste de transporte) y que son exclusivamente las empresas las que presentan un comportamiento estratégico. Most of spatial competition models assume firm decisions exclusively. In these models, custom...
The recent increase in new commercial forms (hypermarkets and shopping centres) in Spain has modified the Spanish retail trade. A conflict of interests has arisen involving the customers, the traditional trade, the promoters of new commercial areas and the Administration. In this work, facility location modelling according to legal conditions is us...
En este trabajo se aplican los modelos de localización, asignación al ámbito escolar. Se estudian problemas de planificación planteados en el contexto de la reforma educativ a definida en la Ley de Ordenación General del Sistema Educativo (LOGSE). Se utiliza el modelo de la p-medianas y se propone un modelo para resolver el problema de la conversió...
Se estudia un problema de localización competitiva en redes. Una firma quiere establecer r centros de servicio en un mercado donde otras firmas competidoras ya disponen de p centros. Los centros pueden estar ubicados en cualquier punto de la red y la demanda se concentra en los nodos. La cantidad de demanda de un nodo que es captada por un centro d...