Revista de Matemáticas 16(2)

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  • Ítem
    Clasificacion automática simbólica por medio de algoritmos genéticos
    (2010-04-09 00:00:00) Fernández Jiménez, Fabio; Murillo Fernández, Álex
        This paper presents a variant in the methods for clustering: a genetic algorithm forclustering through the tools of symbolic data analysis. Their implementation avoidsthe troubles of clustering classical methods: local minima and dependence of datatypes: numerical vectors (continuous data type).    The proposed method was programmed in MatLab R and it uses an interestingoperator of encoding. We compare the clusters by their intra-clusters inertia. We usedthe following measures for symbolic data types: Ichino-Yaguchi dissimilarity measure,Gowda-Diday dissimilarity measure, Euclidean distance and Hausdorff distance.
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    Analysis and Design of the Knowledge Representation for the Implementation of a Distributed Reasoning
    (2011-04-29 00:00:00) Mora Torres, Martha; Laureano Cruces, Ana Lilia; Ramírez Rodríguez, Javier; Espinosa Paredes, Gilberto
    The representation of knowledge and the reasoning comprise fundamental parts of the design of an expert system. In the case under study the real world is represented by the different events that can arise in the operation of a nuclear plant. These events are characterized by a set of elements interrelated through expert reasoning. We have chosen fuzzy cognitive maps (FCM) for the representation of the expert reasoning front to a fault event, because it handles the uncertainty in the decision making, through the interrelation among its elements. In addition, the FCM emphasizes a representation that allows parallel distributed reasoning (PDR). In our work we detail the analysis and design that was developed to build the causality matrices that give origin to the distributed reasoning, and ultimately have a representation in the FCMs.
  • Ítem
    Propiedades de un enfoque difuso para particionamiento con datos bimodales
    (2010-04-09 00:00:00) Castillo Elizondo, William; Trejos Zelaya, Javier
        It is presented a new fuzzy partitioning criterion for two-mode data and an algo-rithm is formulated for its optmization. We study the convergence properties of themethod. The method was tested on real data. It is deduced that better results canbe obtained with this new method than with other methods.Keywords: Two-mode partition, algorithm, fuzzy cluster, minimization, varianceaccounted for.Mathematics Subject Classification: 91C20, 03E72.
  • Ítem
    Asignación de frecuencias en telefonía celular aplicando el problema de coloracion robusta
    (2010-04-09 00:00:00) Lara Velázquez, Pedro; Gallardo López, Lizbeth; Gutiérrez Andrade, Miguel Ángel; de los Cobos Silva, Sergio Gerardo
        The Robust Coloring Problem (RCP) is a NP-Hard Problem for which fast andefficient heuristic algorithms has been developed. In this work we present as a PCRthe problem of assignment of frequencies for a cellphone grid. Some instances for thismodel are proposed and solved using a GRASP algorithm. Evidence shows that theintermittent interruptions in service can be eliminated and the overall capacity can beincreased in approximately 25%.Keywords: Graph coloring, Robust coloring problem, Heuristics, GRASP.
  • Ítem
    Evaluation of air pollution control policies in Mexico City using finite Markov chain observation model
    (2010-04-09 00:00:00) Hoyos, Luis; Lara Velázquez, Pedro; Ortiz, Elba; López Bracho, Rafael; González, Jesús
        This paper proposes a Markov observation based model, where the transition ma-trix is formulated using air quality monitoring data for specific pollutant emissions,with the primary objective to analyze the corresponding stationary distributions andevaluate sceneries for the air quality impact of pollution control policies. The modelis non predictive and could be applied to every source of pollutant emissions includedin air monitoring data. Two cases of study are presented, ozone and sulfur, overcentral zone of Mexico City for a seven years span from 2000 to 2006. For presenta-tion purposes each year were divided in two semesters. In ozone case, the stationarydistribution for both semesters shows a probability diminution of the higher ozone con-centrate levels, with tendency to ”piston effect”. In the sulfur case, the first semesterdisplays an oscillatory behavior with a little tendency to diminution of the higher sul-fur concentrate levels, the second semester had decreasing probabilities of the highersulfur levels. The results support an small improvement of air quality and then a fa-vorable evaluation of the diverse pollution control policies that had been implementedin Mexico City over the last several years.Keywords: Markov chain, stationary distribution, air pollution, sulfur emissions,ozone emissions, Mexico City.
  • Ítem
    Portfolio Optimization Using Particle Swarms with Stripes
    (2011-04-29 00:00:00) Villalobos Arias, Mario Alberto
    In this paper it is consider the Portfolio Optimization Problem developed by Markowitz [11]. The basic assumption is that the investor tries to maximize his/her profit and at the same time, wants to minimize the risk. This problem is usually solved using a scalarization approach (with one objective). Here it is solved it as a bi-objective  optimization problem. It uses a new version of the algorithm of Particle Swarm Optimization for Multi-Objective Problems to which it implemented a method of the stripes to improve dispersion.
  • Ítem
    A mimetic finite difference method using Crank-Nicolson scheme for unsteady diffusion equation
    (2010-04-09 00:00:00) Mannarino, Iliana A.
        n this article a new mimetic finite difference method to solve unsteady diffusionequation is presented. It uses Crank-Nicolson scheme to obtain time approximationsand second order mimetic discretizations for gradient and divergence operators inspace. The convergence of this new method is analyzed using Lax-Friedrichs equiv-alence theorem. This analysis is developed for one dimensional case. In addition tothe analytical work, we provide experimental evidences that mimetic Crank-Nicolsonscheme is better than standard finite difference because it achieves quadratic conver-gence rates, second order truncation errors and better approximations to the exactsolution.Keywords: mimetic scheme, finite difference method, unsteady diffusion equation,Lax-Friedrichs equivalence theorem.
  • Ítem
    About the exact and asymptotic distribution of the Gini coefficient
    (2010-04-09 00:00:00) Martínez Camblor, Pablo; Corral, Norberto
    In this paper we deal with the distribution of the Gini Concentration Index (G).We derive its exact sample distribution which is useful only for small sample sizesand basing on the classic results for L-statistics of Egorov and Nevronov we prove theasymptotic normality for G from an original and probabilistic way.Keywords: Gini Index, Exact Distribution, L-Statistics.