Revista de Matemáticas 17(1)

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https://hdl.handle.net/10669/12965

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    Repeating games and dynamical systems in oil market
    (2010-04-16 00:00:00) Acuña Ortega, Osvaldo; Ulate Montero, Fernán
       We use the modern theory of repetitive games in a model that help understand a market with a cartel like OPEP. We also study a dynamical system Lotka-Volterra type, and we analyze the dynamic behavior of the model.
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    Circular chains of chinese dice
    (2010-04-16 00:00:00) Piza Volio, Eduardo; Schubert, Leo
          In this paper we study Chinese dice, mathematical objects similar to ordinary dice but allowing repetition among their face values.We say that a die A is preferred over a die B (written A B) if A wins more frequently than B does. We study first the existence of circular chains of three dice A, B, C (those that A B C > A) using a mixed integer programming algorithm. Then we generalize the problem to n-dimensional dice—that is, dice of n faces, with n ? 4—and we search circular chains of length m (with m ? 3) using a simulated annealing algorithm. We compare some different objective functions and obtain good solutions to the problem with very efficient algorithms. Finally we obtain a theoretical result concerning the existence of circular chains in the general case.
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    Optimal design of networks and routing of computers: practical case
    (2010-04-16 00:00:00) Pérez Enríquez, Carlos; de los Cobos Silva, Sergio Gerardo
         This work introduced to the problem of routering and optimum design of networks of computers that must satisfy certain practical conditions of interconnectivity. This paper show an approach style Steiner problems, and search robust and more economic solutions.
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    On the stability of certain perturbed systems of differential equations and the relationship with the magnitude of the perturbation
    (2010-04-16 00:00:00) Vázquez Silva, Efrén; Monteiro Chissoca Chitungo, Celso
       In this work we consider a class of polytopes of third order squarematrices, studied early. We obtain a condition to guarantee Hurwitzstability of each of elements of the polytope. This condition is moresimples than one obtained before. Taking into account that to theconsidered set of matrices correspond a family of perturbed sys-tems of differential equations, we study the relationship between thestability condition and the magnitude of the class of perturbationsconsidered for this family.
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    Automatic selection of the p-value in survival curves comparisonautomatic selection of the p-value in survival curves comparison
    (2010-04-16 00:00:00) Martínez Camblor, Pablo
        In this paper, an algorithm for the automatic selection of an ad-equate test for the survival curves comparison is developed. Theintroduced procedure is an adaptation of the double minimum algo-rithm for the bandwidth selection in the smoothed nonparametrick-sample tests. The simulation study which was carried out, sug-gests us that the proposed method, although never is as good as thebest one of the considered tests, is the most regular of them.
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    Latent class analysis in sparse data: alcohol, tobacco and other drugs in teenagers
    (2010-04-16 00:00:00) Araya Alpízar, Carlomagno; Sepúlveda, Rosa
       The contribution of this study is the multidimensional approachon patterns of drug use among young people. The data come fromthe study ”Factors that influence the consumption of drugs, juvenilepopulation. Central region of the West” from Costa Rica, 2006. Onthe basis of the results obtained with a latent class model, 8 sub-groups of individuals settle down according to the consumption ofdifferent drugs.
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    Algebraic jet spaces and Zilber’s dichotomy in DCFA
    (2010-04-16 00:00:00) Bustamante Medina, Ronald F.
    This is the first of two papers devoted to the proof of Zilber’s dichotomy for the case of difference-differential fields of characteristic zero. In this paper we use the techniques exposed in [9] to prove a weaker version of the dichotomy, more precisely, we prove the following: in DCFA the canonical base of a finite-dimensional type is internal to the fixed field of the field of constants. This will imply a weak version of Zilber’s dichotomy: a finite-dimensional type of SU-rank 1 is either 1-based or non-orthogonal to the fixed field of the field of constants.