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Elsevier Science |
Documentos disponibles de esta editorial (162)
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We consider a class of simplification algorithms for algebraic and logical expressions which are of systematic use in computer algebra systems. This class is basically characterized by the fact that algorithms operate in a bottom-up recursive wa[...]texto impreso
Ancochea Bermúdez, José María ; Campoamor Stursberg, Otto Ruttwig ; García Vergnolle, Lucía | Elsevier Science | 2006On montre qu’une algèbre de Lie résoluble rigide réelle n’est pas nécessairement complètement résoluble. On construit un exemple n ? t de dimension minimale dont le tore extérieur t n’est pas formé par des dérivations ad-semi-simples surR. Nous [...]texto impreso
In this paper, we consider a discrete-time queue of Geo/Geo/c type with geometric repeated attempts. It is known that its continuous counterpart, namely the M/M/c queue with exponential retrials, is analytically intractable due to the spatial he[...]texto impreso
In this paper we deal with the main multiserver retrialqueue of M/M/c type with exponential repeated attempts. This model is known to be analytically intractable due to the spatial heterogeneity of the underlying Markov chain, caused by the retr[...]texto impreso
The use of survey plans, which contemplate several tries or call-backs when endeavouring to capture individual data, may supply unarguable information in certain sampling situations with non-ignorable non-response. This paper presents an algorit[...]texto impreso
An algorithm which is valid to estimate the parameters of linear models under several robust conditions is presented. With respect to the robust conditions, firstly, the dependent variables may be either non-grouped or grouped. Secondly, the dis[...]texto impreso
The paper investigates an extension of Christoffel duality to a certain family of Sturmian words. Given an Christoffel prefix w of length N of an Sturmian word of slope g we associate a N-companion slope g(N)* such that the upper Sturmian word o[...]texto impreso
A new family of test statistics for testing linear hypotheses in baseline-category logit models is introduced and its asymptotic distribution is obtained. The new family is a natural extension of the classical likelihood ratio test. A simulation[...]texto impreso
We consider multiserver retrial queues in which the time between two successive repeated attempts is independent of the number of customers applying for service. We study a Markovian model where each arriving customer finding any free server eit[...]texto impreso
In this paper for a wide class of goodness-of-fit statistics based Ko-divergences, the asymptotic normality is established under the assumption n/m(n) --> a is an element of (0, infinity), where m(n) denotes sample size and Mn the number of cel[...]texto impreso
In this paper we prove that given any two disjoint balls in an infinite dimensional complex Banach space, there exists an entire function which is bounded on one and unbounded on the other.texto impreso
We present a framework for solving some types of 0-1 multi-stage scheduling/planning problems under uncertainty in the objective function coefficients and the right-hand-side. A scenario analysis scheme with full recourse is used. The solution o[...]texto impreso
Piqueras de Noriega, Javier ; Díaz-Guerra Viejo, Carlos ; Vila Santos, María | Elsevier Science | 2013-01-25?-Bi_2O-3 microcrystals and microrods with pyramidal tips have been grown by a vapour–solid method using pure Bi as starting material. The morphology of the obtained microstructures depends on the annealing temperature and time. At 650 °C and fo[...]texto impreso
We define (bi)simulations up-to a preorder and show how we can use them to provide a coinductive, (bi)simulation-like, characterisation of semantic (equivalences) preorders for processes. In particular, we can apply our results to all the semant[...]texto impreso
García Ferrero, María Ángeles ; Gómez-Ullate Oteiza, David ; Milson, Robert | Elsevier Science | 2019-04-01It was recently conjectured that every system of exceptional orthogonal polynomials is related to a classical orthogonal polynomial system by a sequence of Darboux transformations. In this paper we prove this conjecture, which paves the road to [...]texto impreso
We discuss the use of bootstrap methodology in hypothesis testing, focusing on the classical F-test for linear hypotheses in the linear model. A modification of the F-statistics which allows for resampling under the null hypothesis is proposed. [...]texto impreso
Gámez Merino, José Luis ; Muñoz-Fernández, Gustavo A. ; Pellegrino, Daniel ; Seoane-Sepúlveda, Juan B. | Elsevier Science | 2012-01In this paper we prove a characterization of continuity for polynomials on a normed space. Namely, we prove that a polynomial is continuous if and only if it maps compact sets into compact sets. We also provide a partial answer to the question a[...]texto impreso
n 1976, Plotkin introduced powerdomains adapting to them, in some sense, Egli- Milner's order. Lately, Smyth (1978) presented the same results starting from generating trees, and adding a new order that he denoted by 0. He also gave a characteri[...]texto impreso
The authors introduce a planar web on a 2-dimensional surface M as a special G -structure. The classical construction by W. Blaschke associates a connection to every planar web. The authors deduce that the Blaschke connection is the only natural onetexto impreso
Marhuenda García, Yolanda ; Morales González, Domingo ; Pardo Llorente, Julio Ángel ; Pardo Llorente, María del Carmen | Elsevier Science | 2005-06-01The testing for goodness-of-fit in multinomial sampling contexts is usually based on the asymptotic distribution of Pearson-type chi-squared statistics. However, approximations are not justified for those cases where sample size and number of ce[...]texto impreso
Feechet-Urysohn (briefly F-U) property for topological spaces is known to be highly non-multiplicative: for instance, the square of a compact F-U space is not in general Frechet-Urysohn [P. Simon, A compact Frechet space whose square is not Frec[...]texto impreso
In this paper we consider the problem of classifying the (n ? 5)-filiform Lie algebras. This is the first index for which infinite parametrized families appear, as can be seen in dimension 7. Moreover we obtain large families of characteristic n[...]texto impreso
In this paper we consider the problem of classifying the (n ? 5)-filiform Lie algebras. This is the first index for which infinite parametrized families appear, as can be seen in dimension 7. Moreover we obtain large families of characteristic n[...]texto impreso
The complete classification of real solvable rigid Lie algebras possessing a nilradical of dimension at most six is given. Eleven new isomorphism classes of indecomposable algebras are obtained. It is further shown that the resulting solvable Li[...]texto impreso
We introduce a notion of regularity for coherent sheaves on Grassmannians of lines. We use this notion to prove some extension of Evans-Griffith criterion to characterize direct sums of line bundles. We also give. in the line of previous results[...]texto impreso
It is shown that for a finite-dimensional solvable rigid Lie algebra r, its rank is upper bounded by the length of the characteristic sequence c(n) of its nilradical n. For any characteristic sequence c = (n(1),..., n(k,) 1), it is proved that t[...]texto impreso
Gómez-Ortiz, David ; Montesinos, F. G. ; Martín Crespo, Tomás ; Solla, Mercedes ; Arnoso, José ; Velez, Emilio | Elsevier Science | 2014-10Timanfaya National Park is a volcanic area located in the southwest of Lanzarote Island (Canary Islands, Spain). Several lava tubes have been found in the lava flows but many others remain unknown. Its location and identification are important t[...]texto impreso
Fe3O4@SiO2 and CoFe2O4@SiO2 and their corresponding amino-functionalized nanocomposites were successfully synthesized by a process of two steps including the preparation by coprecipitation or hydrothermal synthesis of the corresponding magnetic [...]texto impreso
We determine the solvable complete Lie algebras whose nilradical is isomorphic to a filiform Lie algebra. Moreover we show that for any positive integer n there exists a solvable complete Lie algebra whose second cohomology group with values in [...]texto impreso
This note shows that the complete and the ready simulation preorders do not have a finite inequational basis over the language BCCSP when the set of actions is a singleton. Moreover, the equivalences induced by those preorders do not have a fini[...]texto impreso
We study the completeness properties of several different group topologies for the additive group of real numbers, and we also compute the corresponding dual groups. We first present two metrizable connected group topologies on R with topologica[...]texto impreso
Bruguera Padró, M. Montserrat ; Chasco, M.J. ; Martín Peinador, Elena ; Tarieladze, Vaja | Elsevier Science | 2000-04-16It is natural to extend the Grothendieck theorem on completeness, valid for locally convex topological vector spaces, to Abelian topological groups. The adequate framework to do it seems to be the class of locally quasi-convex groups. However, i[...]texto impreso
Nested simulations define an interesting hierarchy of semantic preorders and equivalences in which every semantics refines the previous one and it is refined by the following. This nested nature provides a fruitful framework for the study of the[...]texto impreso
We prove several decidability and undecidability results for ?-PN, an extension of P/T nets with pure name creation and name management. We give a simple proof of undecidability of reachability, by reducing reachability in nets with inhibitor ar[...]texto impreso
We show in this paper that the category of shape can be modelled in discrete terms using maps defined in dense subsets of compacta. This approach to shape provides in addition a characterization of the shape of compacta which does not require ex[...]texto impreso
Barrachina, X. ; Conejero, J. A. ; Murillo Arcila, M. ; Seoane-Sepúlveda, Juan B. | Elsevier Science | 2015-08The interest in car-following models has increased in the last years due to its connection with vehicle-to-vehicle communications and the development of driverless cars. Some non-linear models such as the Gazes–Herman–Rothery model were already [...]texto impreso
We prove a gluing formula for the Donaldson invariants of the connected sum of two fourmanifolds along a surface of genus 2. We also prove a finite type condition for manifolds containing a surface of genus 2, self-intersection zero and represen[...]texto impreso
We give the shape of the Donaldson invariants of a general 4-manifold with b1 = 0 and b+ > 1. The resulting expression involves modular forms and matches the physical predictions.texto impreso
We consider double and (possibly) branched coverings : X ! X0 between real algebraic curves where X is hyperelliptic. We are interested in the topology of such coverings and also in describing them in terms of algebraic equations. In this artic[...]texto impreso
Gamboa, J. M. ; Bujalance, E. ; Conder, M.D.E ; Gromadzki, G. ; Izquierdo, Milagros | Elsevier Science | 2002Let X be a Riemann surface. Two coverings p1 : X ? Y1 and p2 : X ? Y2 are said to be equivalent if p2 =’p1 for some conformal homeomorphism ’: Y1 ? Y2. In this paper we determine, for each integer g¿2, the maximum number R(g) of inequivalent ram[...]texto impreso
Cobos, M.A. ; Presa Muñoz del Toro, Patricia de la ; Llorente, I. ; Garcia Escorial, A. ; Hernando Grande, Antonio ; Jiménez, J.A. | Elsevier Science | 2020-12-30Synthesis and processing methods can have a significant influence on the physical properties of spinel zinc ferrite since it can produce microstructures characterized by different microstructural parameter such as the arrangement of the ions, la[...]texto impreso
We start from the euclidean QCD action for gluons and massless quarks with N_c colours at finite baryon chemical potential ?_B and zero temperature. For ?_B of the order of external momenta o(p) we derive an euclidean effective real chiral lagra[...]texto impreso
For a locally compact group G we consider the class G-M of all proper (in the sense of R. Palais) G-spaces that are metrizable by a G-invariant metric. We show that each X?G-M admits a compatible G-invariant metric whose closed unit balls are sm[...]texto impreso
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We compare Euler–Poincaré reduction in principal fibre bundles, as a constrained variational problem on the connections of this fibre bundle and constraint defined by the vanishing of the curvature of the connection, with the corresponding probl[...]texto impreso
Martínez López, Beatriz ; Ivorra, Benjamin ; Ramos del Olmo, Ángel Manuel ; Fernánez-Carrión, Eduardo ; Alexandrov, Tsviatko ; Sánchez-Vizcaíno, José Manuel | Elsevier Science | 2013-07-26The study presented here is one of the very first aimed at exploring the potential spread of classical swine fever (CSF)from backyard pigs to other domestic pigs. Specifically, we used a spatial stochastic spread model, called Be-FAST, to evalua[...]texto impreso
L’epaississement crustal maximal des Rehamna centraux est acqui par le chevauchement d’0uled Zedness, qui superpose la formation de Jorf El Ahmar (Rehamna orientaux) a la nappe des Skhour (Rehamna centraux) sous un climat metamorphique de moyenn[...]texto impreso
Ovejero, Jesús G. ; Godinho, Vanda ; Lacroix, Bertrand ; García, Miguel A. ; Hernando Grande, Antonio ; Fernández, Asunción | Elsevier Science | 2019-06-05In this paper Co/CoO thick layers (hundreds of nanometers) of different porosity and oxidation degree were prepared in a magnetron sputtering deposition process by tailoring the DC sputtering power, as well as the process gas and target composit[...]texto impreso
In this well-written paper, the authors consider monotone semigroups in ordered spaces and give general results concerning the existence of extremal equilibria and global attractors. \par In the first part of the paper, some notions concerning d[...]texto impreso
Non-additive measures are a valuable tool to model many different problems arising in real situations. However, two important difficulties appear in their practical use: the complexity of the measures and their identification from sample data. F[...]