Inmaculada Espejo

Inmaculada Espejo
Universidad de Cádiz | UCA · Department of Statistics and Operative Research

PhD

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49
Publications
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244
Citations

Publications

Publications (49)
Article
Full-text available
In this paper, we deal with minimum cost b-matching problems on graphs where the nodes are assumed to belong to non-necessarily convex regions called neighborhoods, and the costs are given by the distances between points of the neighborhoods. The goal in the proposed problems is twofold: (i) finding a b-matching in the graph and (ii) determining a...
Conference Paper
Combinatorial optimization has important applications in real world situations. Many such applications can be formulated as optimization problems defined on graphs, this is the case of planning shortest paths, spanning trees, and matching among others. However, many often the exact location of the nodes is unknown and the assumption of modelling th...
Article
This paper deals with the capacitated version of discrete ordered median problems. We present different formulations considering three-index variables or covering variables to address the order requirements in this problem. Some preprocessing phases for fixing variables and some valid inequalities are developed to enhance the initial formulations....
Preprint
Full-text available
The International Workshop on Locational Analysis and Related Problems will take place during January 30-February 1, 2019 in C\'adiz (Spain). It is organized by the Spanish Location Network and Location Group GELOCA (SEIO). GELOCA is a working group on location belonging to the Statistics and Operations Research Spanish Society. The Spanish Locatio...
Preprint
Full-text available
The International Workshop on Locational Analysis and Related Problems will take place during September 27-29, 2017 in Segovia (Spain). It is organized by the Spanish Location Network and Location Group GELOCA (SEIO). GELOCA is a working group on location belonging to the Statistics and Operations Research Spanish Society. The Spanish Location Netw...
Article
This paper deals with a generalized version of the capacitated p-center problem. The model takes into account the possibility that a center might suffer a disruption (being unavailable to serve some demand) and assumes that every site will be covered by its closest available center. The problem is of interest when the goal is to locate emergency ce...
Conference Paper
This work deals with the p-center problem, where the aim is to minimize the maximum distance between any user and his reference center. The reference center for any user will be the second-closest center that will be the center where this user will be reallocated in case of failure of his closest center. Moreover, the capacity of each center must b...
Conference Paper
This work deals with the p-center problem, where the aim is to minimize the maximum distance between any user and his second-closest center. The capacity of each center must suffice to satisfy the demand of all users for which it is the closest center and for the users for which it is the second-closest center because these users will be reallocate...
Conference Paper
This work deals with the p-center problem, where the aim is to minimize the maximum distance between any user and his reference center, considering that in case of failure of any center, the capacities of the remaining centers must suffice to satisfy the demand of all users, taking into account that the users will have as a reference the closest su...
Conference Paper
This paper deals with a generalized version of the capacitated p-center problem. The model takes into account the possibility that a center might suffer a disruption (being unavailable to serve some demand) and assumes that every site will be covered by its closest available center. The problem is of interest when the goal is to locate emergency ce...
Article
The objective of this paper is to identify the most promising sets of closest assignment constraints in the literature of Discrete Location Theory, helping the authors in the field to model their problems when clients must be assigned to the closest plant inside an Integer Programming formulation. In particular, constraints leading to weak Linear P...
Conference Paper
Full-text available
Este trabajo presenta un procedimiento para acelerar la convergencia del algoritmo Weiszfeld en el problema de localización minisum o problema de Weber, cuando las distancias están medidas con una norma lp. Para ello, se combinan los métodos de aceleración basados en la transformación del algoritmo Weiszfeld al introducir un factor de salto función...
Article
This paper presents a location problem on the plane where a single service facility and a rapid transit line have to be simultaneously located. The rapid transit line represents an alternative transportation line which can be used by clients whenever it provides a cost-saving or time-saving service, and it is given by a segment with fixed and known...
Article
This paper presents a solution procedure based on a gradient descent method for the k-centrum problem in the plane. The particular framework of this problem for the Euclidean norm leads to bisector lines whose analytical expressions are easy to handle. This allows us to develop different solution procedures which are tested on different problems an...
Conference Paper
Este trabajo presenta un procedimiento de solución basada en un método de descenso de gradiente para el problema del k-centrum en el plano. El marco particular de este problema para la norma euclídea conduce a que los bisectores tengan expresiones analíticas fáciles de manejar. Esto nos permite desarrollar diferentes procedimientos solución que son...
Article
This paper presents a procedure to solve the convex ordered median problem where the distances are measured with ℓp-norms. In order to do that, we consider an approximated problem and develop an algorithm based on a gradient descent method that generates a sequence with decreasing objective value. We prove its convergence to the optimal solution of...
Article
We consider a discrete facility location problem with a new form of equity criterion. The model discussed in the paper analyzes the case where demand points only have strict preference order on the sites where the plants can be located. The goal is to find the location of the facilities minimizing the total envy felt by the entire set of demand poi...
Conference Paper
En este trabajo se plantea el problema de localizar un servicio y una v��a r�apida de transporte en el plano de modo que se reduzca el tiempo de viaje o se minimicen los costes totales de transporte entre el servicio y los puntos de demanda. Este tipo de problemas no ha sido estudiado hasta el momento, ya que los modelos que podemos encontrar en la...
Conference Paper
En este trabajo se presentan resultados de convergencia para el problema de localizaci �on minisum cuando las distancias entre los puntos de demanda y el servicio a localizar est�an medidas con normas lp, para valores de p mayores que 2. Se proponen procedimientos de resoluci�on para este problema, extendiendo as�� los resultados conocidos para p e...
Book
Full-text available
Manual para alumnos de titulaciones experimentales que proporciona una visión práctica e intuitiva de la estadística descriptiva y el cálculo de probabilidades, campos básicos y fundamentales de la ciencia estadística
Article
Full-text available
This paper considers a location problem in ℝ n , where the demand is not necessarily concentrated at points but it is distributed in hypercubes following a Uniform probability distribution. The goal is to locate a service facility minimizing the weighted sum of average distances (measured with ℓ p norms) to these demand hypercubes. In order to do...
Book
Full-text available
Manual en seis capítulos dedicado a la inferencia estadística. Se tratan en sus páginas temas como la estimación puntual, la estimación por intervalos, el contraste por hipótesis, los contrastes no paramétricos y la varianza.
Conference Paper
Full-text available
In this paper we develop a procedure to solve a generalization of the Weber Problem. The goal of this problem is to locate a service facility to cover the demand of a region. This demand is modelled by a random variable with a known distribution probability. In order to solve the problem, we propose a descomposition and approximation of this distri...
Book
Full-text available
El presente libro recoge una selección de los trabajos presentados a la Conferencia Internacional de Estadística en Estudios Medioambientales, EMA’01, que se celebró en Cádiz en Noviembre de 2001. Los trabajos seleccionados han pasado un proceso de revisión en el que se han considerado tanto aspectos científicos como de oportunidad. En este sentido...

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