# Revista de Matemáticas 13(2)

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Ítem Estudio de las condiciones de desarrollo de un conjunto de distritos de la república de panamá(2009-02-20 00:00:00) Díaz, Juan; Carrasco, GonzaloMás... Through the Principal Components the weights of each one of the variables arereflected and as well they will allow to group the districts of the Republic of Panamain similar conditions of development groups and thus for determining the similaritiesand inequalities.Keywords: principal component, eigenvalue, eigenvector, correlation matrix, variancecovariancematrix, orthogonal, district, development.Más... Ítem Algoritmos evolutivos en la solución de problemas de estimación de parámetros(2009-02-20 00:00:00) Marrero Severo, Aymée de los Ángeles; Pedroso Rodríguez, Liuva M.; Barrios Ginart, JorgeMás... The global problem to determine the values of some parameters in dynamicalmodels knowing experimental results is frequently known as Parameters EstimationProblem and it appears in many areas of sciences. So is clear that there are many waysto obtain a famuly of parametersvalues that satisfy the satated conditions. This workshows some experiences in the treatment of this kind of models when the constraintsare ordinary differential equations using evolutive algorithms. Our aim is to showthat another ways can be usefull too to solve this problem with similar facilities andefficiency.Keywords: Estimation of parameters problem, dynamical systems, genetic or evolutivealgorithm.Más... Ítem Heuristic analysis of a near optimal approximation algorithm for the determination of investment options(2009-02-20 00:00:00) Flores, Juan; Ávila, Javier; González, Federico; Flores Romero, BeatrizMás... When cash becomes available in a company, there are several strategies that allowus to benefit from it. The problem is how much to invest, for how long, and using whichof the investment options in order to get the maximum profit out of it. A commonproblem in business administration is that we do not want to keep the money idle inthe checking account, neither to over-invest. When the cash function becomes negativean analogous scheme is used as we want to pay as little interests as possible. In thispaper we are reporting the experiments and implementation of several heuristics thatcan be used with the greedy algorithm and how well they behave. Finally we developa hybrid algorithm that takes the best of the greedy algorithm and performs a verylimited search. We find in this work that with the greedy algorithm we use, in generalis not possible to optimize the profit for a given function; nevertheless the algorithmwe use can find profits that are very close to the optimum and in some cases it getsthe optimum. The proposed algorithm use a heuristic search based on the greedyscheme and greedy selection criteria to find profits close to the optimum. A softwareapplication was developed in order to show that the proposed strategy really works.Although this algorithm is suboptimal, it is very efficient in terms of time.Keywords: Common sense reasoning, knowledge representation,soft decision making,greedy algorithms, financial analysis.Más... Ítem New results with scatter search applied to multiobjective combinatorial and nonlinear optimization problems(2009-02-20 00:00:00) Beausoleil, Ricardo P.Más... This paper introduces two variants of a multiple criteria scatter search to deal withnonlinear continuous and combinatorial problems, applying a tabu search approach asa diversification generator method. Frequency memory and another escape mechanismare used to diversify the search. A Pareto relation is applied in order to designatea subset of the best generated solutions to be reference solutions. A choice functioncalled Kramer Choice is used to divide the reference solution in two subsets. Euclideanand Hamming distances are used as measures of dissimilarity in order to find diversesolutions to complement the subsets of high quality current Pareto solutions to becombined. Linear combination and path relinking are used as a combination methods.The performance of these approaches are evaluated on several test problems taken fromthe literature.Keywords: Multiple objectives, metaheuristics, tabu search, scatter search, nonlinearoptimization.Más... Ítem Anillos separables, de baer y pp-anillos(2009-02-20 00:00:00) Guier Acosta, Jorge IgnacioMás... Keimel introduced the notion of proyectability in the class of lattice-ordered ringsand f-rings in [5]. Here we introduce a similar notion forgeting the lattice and orderedstructure of the ring and interpretating the orthogonality within the multiplicativestructure (in the class of reduced rings). This notion turns out to be equivalent to theone defining the class of PP-rings and it is related to the compactness of the space ofthe minimal primes ideals and to the class of weak Baer rings.Keywords: Boolean products, elementary class, continuous sections, Baer rings, PPrings,minimal prime ideales.Más... Ítem Condiciones generales para la construcción de modelos de ˆb 2 ? LmIND(2009-02-20 00:00:00) Chinchilla, EugenioMás... We give general conditions that are sufficient to prove existence of models of ˆb2 ? LmIND inside a special set.Keywords: weak arithmetic, non standard model, complexity classes.Más... Ítem Una caracterización sobre las soluciones para el problema de reaprovisionamiento conjunto(2009-02-20 00:00:00) de los Cobos Silva, Sergio Gerardo; Gutiérrez Andrade, Miguel Ángel; Goddard Close, John; Pérez Salvador, Blanca RosaMás... In this paper an introduction is given to a multiple-item inventory problem, knownas the Joint Replenishment Problem (JRP). This is a real world problem which hasbeen extensively studied. The JRP has a continuous decision variable, and as manydiscrete decision variables as products that are ordered and produced. An exactmethod, given by Goyal, exists for solving the JRP, however for a large number of discrete decision variables the computational time required becomes prohibitive. Here,an alternative characterization of the solution for the combinatorial part of the JRPis given.Keywords: Inventory mutiple-item problems, joint replenishment problem.Más...