Revista de Matemáticas 6(2)

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  • Ítem
    Un frailty aditivo en modelos de supervivencia bivariante
    (2009-02-18 00:00:00) Navarrete Álvarez, Esteban; García Leal, Julia; Lara Porras, Ana María
    Bivariate survival models based on the presence of an unobseved random covariate, grailty, tend to assume a proportional hazard hypothesis. A bivariate survival model is constructed. It is based on frailty model that acts additivelky on the hazard function.Keywords: survival times, frailty, dependence, proportional risk.
  • Ítem
    Un enfoque diferente de las técnicas de clustering para el estudio de epidemias
    (2009-02-18 00:00:00) Casas Cardoso, Gladys M.; Grau Abalo, Ricardo
    Classification of an outbreak with the category of epidemics requires that some epidemiological and statistical parameters, which have to be studied simultaneously, are satisfied; mathematical theory helps epidemiologists indetection of epidemics in cases when it is not evident. At the present time, these situations ares studied with slutering techniques, with the help of specialized software inthese topics. The present work aims to study these techniques and its imporvement with including risk factors. It is also presented an application with real data.Keywords: disease clusters, space time interaction, Scan statistics.
  • Ítem
    Optimiza - un paquete computacional para la optimización de problemas no lineales
    (2009-02-18 00:00:00) Palencia F., Gonzalo; Molina P., Vicente; Llano R., Venzyslav
    Our goal is to build a software able to solve problems in non linear optimization. A central point is selection of the algorithm, which is based on Augmented Lagrangian Method combined with quasi-Newton methods (BFGS, L-BFGS). The article expains how software is structured, the steps of its construction and the mode of use; furthermore, results ansd numerical tests are analyzed. OPTIMIZA 3.0 was built on Borland Delphi 3.0 and runs on Windows, its capacity on the number of variables and constraints are ontly limited ont he memory machine to be used.keywords: Nonlinear optimization, constrained optimization, mathematical programming,  nonlinear porgramming, optimization.
  • Ítem
    Goal problems in gambling theory
    (2009-02-18 00:00:00) Hill, Theodore
    A short introduction to goal problems in abstract gambling theory is given, along with statementes of some of the main theorems and a number of examples, open problems and references. Emphasis is on the finite-state, countably-additive setting with such classical objectives as reaching a goal, hitting a goal  infinitely often, staying in the goal, and maximizing the average time spent at a goal.keywords: gambling theory, stochastic processes, Markov strategies.
  • Ítem
    El espacio cociente y algunas propiedades geométricas de los espacios de Banach
    (2009-02-18 00:00:00) Morales, José R.
    We state some geometric properties of Banach spaces, such as uniformly convex spaces, uniformly non-square spaces, local uniformly convex spaces, strictly convex spaces, etc., and we analyze the problem of translating such properties to the quotient space.keywords: uniformly convex sapce, uniformly non-squere sapce, LUR space, (R) space.
  • Ítem
    Ultraproductos de f-anillos proyectables
    (2009-02-18 00:00:00) Guier Acosta, Jorge Ignacio
    In [7], Keimel representes the projectable f-rings as continuous sections of Hausdorff sheaves of totally ordered rings. Here, we give a result about the representation of ultraporducts of projectable f-rings in terms of the representation spaces  and the stalks of its factors.Keywords: Boolean products, elementary class, ultracoproduct of compact spaces, continuous sections.
  • Ítem
    Relations of k-th derivative of dirac delta in hypercone with ultrahyperbolic operator
    (2009-02-18 00:00:00) Aguirre T., Manuel A.
    In this paper we prove that the generalized functions d (k) (P+) - d (k) (P), d (k) (P-)-d (k) (-P) and d 1 (k) (P)-d 2 (k) (P)d are concentrated in the vertex of the cone P=0 and we find their relationship with the ultrahyperbolic operator iterated (k +1 -n/2 ) times under condition k ³ n/2-1Keywords: distributions, generalized functions, distributions spaces, properties of distributions.