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Mostrando ítems 572-591 de 753

    • closedAccess   R-factorizable paratopological groups 

      Sanchis López, Manuel; Tkachenko, Mikhail Elsevier (2010)
      For i = 1, 2, 3, 3.5, we define the class of R<sub>i</sub>-factorizable paratopological groups G by the condition that every continuous real-valued function on G can be factorized through a continuous homomorphism p : G → ...

    • closedAccess   Radon-Nikodým derivatives for vector measures belonging to Köthe function spaces 

      Calabuig, J. M.; Gregori, Pablo; Sánchez Pérez, Enrique A. Elsevier (2008)
      Let m, n be a couple of vector measures with values on a Banach space. We develop a separation argument which provides a characterization of when the Radon-Nikodým derivative of n with respect to m-in the sense of the ...

    • openAccess   Random non-autonomous second order linear differential equations: mean square analytic solutions and their statistical properties 

      Calatayud, Julia; Cortés, Juan Carlos; Jornet, Marc; Villafuerte, L. Springer (2018-10-24)
      In this paper we study random non-autonomous second order linear differential equations by taking advantage of the powerful theory of random difference equations. The coefficients are assumed to be stochastic processes, ...

    • openAccess   Rational maps with Fatou components of arbitrarily large connectivity 

      Canela, Jordi Elsevier (2018-02-02)
      We study the family of singular perturbations of Blaschke products . We analyse how the connectivity of the Fatou components varies as we move continuously the parameter λ. We prove that all possible escaping configurations ...

    • openAccess   Real-Linear Isometries and Jointly Norm-Additive Maps on Function Algebras 

      Hosseini, Maliheh; Font, Juan J. Springer (2015)
      In this paper, we describe into real-linear isometries defined between (not necessarily unital) function algebras and show, based on an example, that this type of isometries behaves differently from surjective real-linear ...

    • openAccess   Real-Multilinear Isometries on Function Algebras 

      Font, Juan J.; Hosseini, Maliheh Springer International Publishing (2017)
      Let A 1 ,...,A k be function algebras (or more generally, dense subspaces of uniformly closed function algebras) on locally compact Haus- dorff spaces X 1 ,...,X k , respectively, and let Y be a locally ...

    • closedAccess   Reality, Systems and Impure Systems 

      Nescolarde-Selva, J.; Usó Doménech, Josep Lluís Springer (2014)
      Impure systems contain Objects and Subjects: Subjects are human beings. We can distinguish a person as an observer (subjectively outside the system) and that by definition is the Subject himself, and part of the system. ...

    • closedAccess   Recent advances to model anisotropic space–time data 

      Mateu, Jorge; Porcu, Emilio; Gregori, Pablo Springer-Verlag (2008-05)
      Building new and flexible classes of nonseparable spatio-temporal covariances and variograms has resulted a key point of research in the last years. The goal of this paper is to present an up-to-date overview of recent ...

    • openAccess   Reconstrucción cognitiva de los conceptos centrales de la función exponencial: un estudio de enfoque mixto 

      Rodríguez, Miguel A.; Ledezma Araya, Carlos Andrés; Vergara Gómez, Andrea Stephanie; Gregori, Pablo Centro de Informacion Tecnologica (2021)
      Este estudio presenta evidencias sobre la validación de un modelo cognitivo llamado descomposición genética para la reconstrucción del concepto función exponencial. Se encuesta a 22 estudiantes del profesorado de matemática ...

    • openAccess   Reflections in topological algebraic structures 

      HERNÁNDEZ ARZUSA, JULIO CÉSAR; Hernández, Salvador Elsevier (2020-08)
      Let C be an epireflective subcategory of Top and let rC be the epireflective functor associated with C. If A denotes a (semi)topological algebraic subcategory of Top, we study when rC (A) is an epireflective subcategory ...

    • openAccess   Reflexivity in precompact groups and extensions 

      Galindo, Jorge; Tkachenko, Mikhail; Bruguera, Montserrat; Hernández, Constancio Elsevier (2014-02)
      We establish some general principles and find some counter-examples concerning the Pontryagin reflexivity of precompact groups and P-groups. We prove in particular that: (1) A precompact Abelian group G of ...

    • closedAccess   Reflexivity of prodiscrete topological groups  

      Galindo, Jorge; Recoder Núñez, Luis; Tkachenko, Mikhail Elsevier (2011)
      We study the duality properties of two rather different classes of subgroups of direct products of discrete groups (protodiscrete groups): P-groups, i.e., topological groups such that countable intersections of its open ...

    • openAccess   Reliability Evaluation of the Data Acquisition Potential of a Low-Cost Climatic Network for Applications in Agriculture 

      Trilles, Sergio; Juan, Pablo; Díaz-Avalos, Carlos; Ribeiro, Sara; Painho, Marco MDPI (2020)
      Temperature, humidity and precipitation have a strong influence on the generation of diseases in different crops, especially in vine. In recent years, advances in different disciplines have enabled the deployment of sensor ...

    • openAccess   Reliability Validation of a Low-Cost Particulate Matter IoT Sensor in Indoor and Outdoor Environments Using a Reference Sampler 

      Trilles, Sergio; Vicente, Ana Belen; Juan, Pablo; Ramos, Jose Francisco; Meseguer Costa, Sergio; Serra, Laura MDPI (2019)
      A suitable and quick determination of air quality allows the population to be alerted with respect to high concentrations of pollutants. Recent advances in computer science have led to the development of a high number of ...

    • openAccess   Representation and approximation by series of continuous functions 

      Hernández, Salvador; Gassó Matoses, María Teresa; Rojas Bernilla, Esptiben Springer Verlag (2008)
      Let X be a topological space and let C (X) be the ring of all real-valued continuous functions defined on X. In this paper, we study the representation and approximation of continuous functions by sums of infinite series. ...

    • openAccess   Representation of group isomorphisms I 

      Ferrer González, María Vicenta; Gary Gutierrez, Margarita; Hernández, Salvador Elsevier (2019-08-15)
      Let G be a metric group and let Aut(G) denote the automorphism group of G. If A and B are groups of G-valued maps defined on the sets X and Y , respec- tively, we say that A and B are equivalent if there is a group ...

    • openAccess   Representation of Group Isomorphisms: The Compact Case 

      Ferrer González, María Vicenta; Gary Gutierrez, Margarita; Hernández, Salvador Hindawi Publishing Corporation (2015)
      Let 𝐺� be a discrete group and let A and B be two subgroups of 𝐺�-valued continuous functions defined on two 0-dimensional compact spaces 𝑋� and 𝑌�. A group isomorphism 𝐻� defined between A and B is called separating ...

    • openAccess   Resample-smoothing of Voronoi intensity estimators 

      Moradi, Mehdi; Cronie, Ottmar; Rubak, Ege; Lachieze-Rey, Raphael; Mateu, Jorge Springer (2019)
      Voronoi estimators are non-parametric and adaptive estimators of the intensity of a point process. The intensity estimateat a given location is equal to the reciprocal of the size of the Voronoi/Dirichlet cell containing ...

    • openAccess   Residual kriging for functional data. Application to the spatial prediction of salinity curves 

      Reyes, Adriana; Giraldo, Ramón; Mateu, Jorge Taylor & Francis (2015)
      Recently several methodologies for carrying out geostatistical analysis of functional data has been proposed. All of them assume that the spatial functional process considered is stationary. However in practice we often ...

    • closedAccess   Restrictions on maximal invariant subgroups implying solvability of finite groups 

      Beltrán, Antonio; shao, Changguo Springer Verlag (2018)
      Suppose that G and A are finite groups such that A acts coprimely on G via automorphisms. It is interesting to investigate the structure and properties of G when we impose some restrictions on its maximal A-invariant ...