Articles de revista
http://hdl.handle.net/2117/3430
Tue, 28 Jan 2020 08:24:09 GMT
20200128T08:24:09Z

The Banzhaf value for cooperative and simple multichoice games
http://hdl.handle.net/2117/175430
The Banzhaf value for cooperative and simple multichoice games
Freixas Bosch, Josep
This article proposes a value which can be considered an extension of the Banzhaf value for cooperative games. The proposed value is defined on the class of jcooperative games, i.e., games in which players choose among a finite set of ordered actions and the result depends only on these elections. If the output is binary, only two options are available, then jcooperative games become jsimple games. The restriction of the value to jsimple games leads to a power index that can be considered an extension of the Banzhaf power index for simple games. The paper provides an axiomatic characterization for the value and the index which is closely related to the first axiomatization of the Banzhaf value and Banzhaf power index in the respective contexts of cooperative and simple games.
This is a postpeerreview, precopyedit version of an article published in Group Decision and Negotiation. The final authenticated version is available online at: https://doi.org/10.1007/s10726019096514.
Wed, 22 Jan 2020 12:23:36 GMT
http://hdl.handle.net/2117/175430
20200122T12:23:36Z
Freixas Bosch, Josep
This article proposes a value which can be considered an extension of the Banzhaf value for cooperative games. The proposed value is defined on the class of jcooperative games, i.e., games in which players choose among a finite set of ordered actions and the result depends only on these elections. If the output is binary, only two options are available, then jcooperative games become jsimple games. The restriction of the value to jsimple games leads to a power index that can be considered an extension of the Banzhaf power index for simple games. The paper provides an axiomatic characterization for the value and the index which is closely related to the first axiomatization of the Banzhaf value and Banzhaf power index in the respective contexts of cooperative and simple games.

Numerical analysis of a dualphaselag model involving two temperatures
http://hdl.handle.net/2117/175293
Numerical analysis of a dualphaselag model involving two temperatures
Bazarra, Noelia; Fernández, José Ramón; Magaña Nieto, Antonio; Quintanilla de Latorre, Ramón
In this paper, we numerically analyse a phaselag model with two temperatures which arises in the heat conduction theory. The model is written as a linear partial differential equation of third order in time. The variational formulation, written in terms of the thermal acceleration, leads to a linear variational equation, for which we recall an existence and uniqueness result and an energy decay property. Then, using the finite element method to approximate the spatial variable and the implicit Euler scheme to discretize the time derivatives, fully discrete approximations are introduced. A discrete stability property is proved, and a priori error estimates are obtained, from which the linear convergence of the approximation is derived. Finally, some onedimensional numerical simulations are described to demonstrate the accuracy of the approximation and the behaviour of the solution.
Mon, 20 Jan 2020 13:43:55 GMT
http://hdl.handle.net/2117/175293
20200120T13:43:55Z
Bazarra, Noelia
Fernández, José Ramón
Magaña Nieto, Antonio
Quintanilla de Latorre, Ramón
In this paper, we numerically analyse a phaselag model with two temperatures which arises in the heat conduction theory. The model is written as a linear partial differential equation of third order in time. The variational formulation, written in terms of the thermal acceleration, leads to a linear variational equation, for which we recall an existence and uniqueness result and an energy decay property. Then, using the finite element method to approximate the spatial variable and the implicit Euler scheme to discretize the time derivatives, fully discrete approximations are introduced. A discrete stability property is proved, and a priori error estimates are obtained, from which the linear convergence of the approximation is derived. Finally, some onedimensional numerical simulations are described to demonstrate the accuracy of the approximation and the behaviour of the solution.

A problem with viscoelastic mixtures: numerical analysis and computational experiments
http://hdl.handle.net/2117/173986
A problem with viscoelastic mixtures: numerical analysis and computational experiments
Fernández, José Ramón; Masid, Maria; Magaña Nieto, Antonio; Quintanilla de Latorre, Ramón
In this paper, we study, from the numerical point of view, a dynamic problem involving a mixture of two viscoelastic solids. The mechanical problem is written as a system of two coupled partial differential equations. Its variational formulation is derived and an existence and uniqueness result, and an energy decay property, are recalled. Then, fully discrete approximations are introduced by using the classical finite element method and the implicit Euler scheme. A discrete stability property and a priori error estimates are shown, from which we deduce the linear convergence of the algorithm. Finally, some numerical simulations, including examples in one and two dimensions, are presented to show the accuracy of the approximation and the behaviour of the solution.
Mon, 16 Dec 2019 13:16:02 GMT
http://hdl.handle.net/2117/173986
20191216T13:16:02Z
Fernández, José Ramón
Masid, Maria
Magaña Nieto, Antonio
Quintanilla de Latorre, Ramón
In this paper, we study, from the numerical point of view, a dynamic problem involving a mixture of two viscoelastic solids. The mechanical problem is written as a system of two coupled partial differential equations. Its variational formulation is derived and an existence and uniqueness result, and an energy decay property, are recalled. Then, fully discrete approximations are introduced by using the classical finite element method and the implicit Euler scheme. A discrete stability property and a priori error estimates are shown, from which we deduce the linear convergence of the algorithm. Finally, some numerical simulations, including examples in one and two dimensions, are presented to show the accuracy of the approximation and the behaviour of the solution.

On the linear thermoelasticity with two porosities: numerical aspects
http://hdl.handle.net/2117/171631
On the linear thermoelasticity with two porosities: numerical aspects
Bazarra, Noelia; Fernández, José Ramón; Leseduarte Milán, María Carme; Magaña Nieto, Antonio; Quintanilla de Latorre, Ramón
In this work we analyze, from the numerical point of view, a dynamic problem involving a thermoelastic rod. Two porosities are considered: the first one is the macroporosity, connected with the pores of the material, and the other one is the microporosity, linked with the fissures of the skeleton. The mechanical problem is written as a set of hyperbolic and parabolic partial differential equations. An existence and uniqueness result and an energy decay property are stated. Then, a fully discrete approximation is introduced using the finite element method and the backward Euler scheme. A discrete stability property and a priori error estimates are proved, from which the linear convergence of the algorithm is derived under suitable additional regularity conditions. Finally, some numerical simulations are presented to show the behaviour of the approximation
Tue, 05 Nov 2019 08:19:09 GMT
http://hdl.handle.net/2117/171631
20191105T08:19:09Z
Bazarra, Noelia
Fernández, José Ramón
Leseduarte Milán, María Carme
Magaña Nieto, Antonio
Quintanilla de Latorre, Ramón
In this work we analyze, from the numerical point of view, a dynamic problem involving a thermoelastic rod. Two porosities are considered: the first one is the macroporosity, connected with the pores of the material, and the other one is the microporosity, linked with the fissures of the skeleton. The mechanical problem is written as a set of hyperbolic and parabolic partial differential equations. An existence and uniqueness result and an energy decay property are stated. Then, a fully discrete approximation is introduced using the finite element method and the backward Euler scheme. A discrete stability property and a priori error estimates are proved, from which the linear convergence of the algorithm is derived under suitable additional regularity conditions. Finally, some numerical simulations are presented to show the behaviour of the approximation

On the time decay in phaselag thermoelasticity with two temperatures
http://hdl.handle.net/2117/170281
On the time decay in phaselag thermoelasticity with two temperatures
Magaña Nieto, Antonio; Miranville, Alain; Quintanilla de Latorre, Ramón
The aim of this paper is to study the time decay of the solutions for two models of the onedimensional phaselag thermoelasticity with two temperatures. The first one is obtained when the heat flux vector and the inductive temperature are approximated by a secondorder and firstorder Taylor polynomial, respectively. In this case, the solutions decay in a slow way. The second model that we consider is obtained taking
firstorder Taylor approximations for the inductive thermal displacement, the inductive temperature and the heat flux. The decay is, therefore, of exponential type.
Wed, 16 Oct 2019 15:51:40 GMT
http://hdl.handle.net/2117/170281
20191016T15:51:40Z
Magaña Nieto, Antonio
Miranville, Alain
Quintanilla de Latorre, Ramón
The aim of this paper is to study the time decay of the solutions for two models of the onedimensional phaselag thermoelasticity with two temperatures. The first one is obtained when the heat flux vector and the inductive temperature are approximated by a secondorder and firstorder Taylor polynomial, respectively. In this case, the solutions decay in a slow way. The second model that we consider is obtained taking
firstorder Taylor approximations for the inductive thermal displacement, the inductive temperature and the heat flux. The decay is, therefore, of exponential type.

Exponential stability in threedimensional type III thermoporouselasticity with microtemperatures
http://hdl.handle.net/2117/170099
Exponential stability in threedimensional type III thermoporouselasticity with microtemperatures
Magaña Nieto, Antonio; Quintanilla de Latorre, Ramón
We study the time decay of the solutions for the type III thermoelastic theory with microtemperatures and voids. We prove that, under suitable conditions for the constitutive tensors, the solutions decay exponentially. This fact is in somehow striking because it differs from the behaviour of the solutions in the classical model of thermoelasticity with microtemperatures and voids, where the exponential decay is not expected in the general case.
Tue, 15 Oct 2019 09:59:10 GMT
http://hdl.handle.net/2117/170099
20191015T09:59:10Z
Magaña Nieto, Antonio
Quintanilla de Latorre, Ramón
We study the time decay of the solutions for the type III thermoelastic theory with microtemperatures and voids. We prove that, under suitable conditions for the constitutive tensors, the solutions decay exponentially. This fact is in somehow striking because it differs from the behaviour of the solutions in the classical model of thermoelasticity with microtemperatures and voids, where the exponential decay is not expected in the general case.

The neighborhood role in the linear threshold rank on social networks
http://hdl.handle.net/2117/169655
The neighborhood role in the linear threshold rank on social networks
Riquelme Csori, Fabián; Gonzalez Cantergiani, Pablo; Molinero Albareda, Xavier; Serna Iglesias, María José
Centrality and influence spread are two of the most studied concepts in social network analysis. Several centrality measures, most of them, based on topological criteria, have been proposed and studied. In recent years new centrality measures have been defined inspired by the two main influence spread models, namely, the Independent Cascade Model (ICmodel) and the Linear Threshold Model (LTmodel). The Linear Threshold Rank (LTR) is defined as the total number of influenced nodes when the initial activation set is formed by a node and its immediate neighbors. It has been shown that LTR allows to rank influential actors in a more distinguishable way than other measures like the PageRank, the Katz centrality, or the Independent Cascade Rank. In this paper we propose a generalized LTR measure that explore the sensitivity of the original LTR, with respect to the distance of the neighbors included in the initial activation set. We appraise the viability of the approach through different case studies. Our results show that by using neighbors at larger distance, we obtain rankings that distinguish better the influential actors. However, the best differentiating ranks correspond to medium distances. Our experiments also show that the rankings obtained for the different levels of neighborhood are not highly correlated, which validates the measure generalization
Thu, 10 Oct 2019 11:30:23 GMT
http://hdl.handle.net/2117/169655
20191010T11:30:23Z
Riquelme Csori, Fabián
Gonzalez Cantergiani, Pablo
Molinero Albareda, Xavier
Serna Iglesias, María José
Centrality and influence spread are two of the most studied concepts in social network analysis. Several centrality measures, most of them, based on topological criteria, have been proposed and studied. In recent years new centrality measures have been defined inspired by the two main influence spread models, namely, the Independent Cascade Model (ICmodel) and the Linear Threshold Model (LTmodel). The Linear Threshold Rank (LTR) is defined as the total number of influenced nodes when the initial activation set is formed by a node and its immediate neighbors. It has been shown that LTR allows to rank influential actors in a more distinguishable way than other measures like the PageRank, the Katz centrality, or the Independent Cascade Rank. In this paper we propose a generalized LTR measure that explore the sensitivity of the original LTR, with respect to the distance of the neighbors included in the initial activation set. We appraise the viability of the approach through different case studies. Our results show that by using neighbors at larger distance, we obtain rankings that distinguish better the influential actors. However, the best differentiating ranks correspond to medium distances. Our experiments also show that the rankings obtained for the different levels of neighborhood are not highly correlated, which validates the measure generalization

An axiomatization for two power indices for (3,2)simple games
http://hdl.handle.net/2117/133317
An axiomatization for two power indices for (3,2)simple games
Bernardi, Giulia; Freixas Bosch, Josep
The aim of this work is to give a characterization of the Shapley–Shubik and the Banzhaf power indices for (3,2)simple games. We generalize to the set of (3,2)simple games the classical axioms for power indices on simple games: transfer, anonymity, null player property and efficiency. However, these four axioms are not enough to uniquely characterize the Shapley–Shubik index for (3,2)simple games. Thus, we introduce a new axiom to prove the uniqueness of the extension of the Shapley–Shubik power index in this context. Moreover, we provide an analogous characterization for the Banzhaf index for (3,2)simple games, generalizing the four axioms for simple games and adding another property.
Electronic version of an article published as International Game Theory Review, Vol. 21, Issue 1, 1940001, 2019, p. 124. DOI: 10.1142/S0219198919400012] © World Scientific Publishing Company https://wwwworldscientificcom.recursos.biblioteca.upc.edu/doi/abs/10.1142/S0219198919400012
Wed, 22 May 2019 08:45:25 GMT
http://hdl.handle.net/2117/133317
20190522T08:45:25Z
Bernardi, Giulia
Freixas Bosch, Josep
The aim of this work is to give a characterization of the Shapley–Shubik and the Banzhaf power indices for (3,2)simple games. We generalize to the set of (3,2)simple games the classical axioms for power indices on simple games: transfer, anonymity, null player property and efficiency. However, these four axioms are not enough to uniquely characterize the Shapley–Shubik index for (3,2)simple games. Thus, we introduce a new axiom to prove the uniqueness of the extension of the Shapley–Shubik power index in this context. Moreover, we provide an analogous characterization for the Banzhaf index for (3,2)simple games, generalizing the four axioms for simple games and adding another property.

Measuring satisfaction and power in influence based decision systems
http://hdl.handle.net/2117/132016
Measuring satisfaction and power in influence based decision systems
Molinero Albareda, Xavier; Riquelme Csori, Fabián; Serna Iglesias, María José
We introduce collective decisionmaking models associated with influence spread under the linear threshold model in social networks. We define the oblivious and the nonoblivious influence models. We also introduce the generalized opinion leader–follower model (gOLF) as an extension of the opinion leader–follower model (OLF) proposed by van den Brink et al. (2011). In our model we allow rules for the final decision different from the simple majority used in OLF. We show that gOLF models are nonoblivious influence models on a twolayered bipartite influence digraph. Together with OLF models, the satisfaction and the power measures were introduced and studied. We analyze the computational complexity of those measures for the decision models introduced in the paper. We show that the problem of computing the satisfaction or the power measure is #Phard in all the introduced models even when the subjacent social network is a bipartite graph. Complementing this result, we provide two subfamilies of decision models in which both measures can be computed in polynomial time. We show that the collective decision functions are monotone and therefore they define an associated simple game. We relate the satisfaction and the power measures with the Rae index and the Banzhaf value of an associated simple game. This will allow the use of known approximation methods for computing the Banzhaf value, or the Rae index to their practical computation.
Thu, 25 Apr 2019 11:46:03 GMT
http://hdl.handle.net/2117/132016
20190425T11:46:03Z
Molinero Albareda, Xavier
Riquelme Csori, Fabián
Serna Iglesias, María José
We introduce collective decisionmaking models associated with influence spread under the linear threshold model in social networks. We define the oblivious and the nonoblivious influence models. We also introduce the generalized opinion leader–follower model (gOLF) as an extension of the opinion leader–follower model (OLF) proposed by van den Brink et al. (2011). In our model we allow rules for the final decision different from the simple majority used in OLF. We show that gOLF models are nonoblivious influence models on a twolayered bipartite influence digraph. Together with OLF models, the satisfaction and the power measures were introduced and studied. We analyze the computational complexity of those measures for the decision models introduced in the paper. We show that the problem of computing the satisfaction or the power measure is #Phard in all the introduced models even when the subjacent social network is a bipartite graph. Complementing this result, we provide two subfamilies of decision models in which both measures can be computed in polynomial time. We show that the collective decision functions are monotone and therefore they define an associated simple game. We relate the satisfaction and the power measures with the Rae index and the Banzhaf value of an associated simple game. This will allow the use of known approximation methods for computing the Banzhaf value, or the Rae index to their practical computation.

On the uniqueness and analyticity in viscoelasticity with double porosity
http://hdl.handle.net/2117/131999
On the uniqueness and analyticity in viscoelasticity with double porosity
Bazarra, Noelia; Fernández, José Ramón; Leseduarte Milán, María Carme; Magaña Nieto, Antonio; Quintanilla de Latorre, Ramón
In this paper we analyze the system of equations that models the behaviour of materials with a double porous structure. We introduce dissipation mechanisms in both structures. We show existence, uniqueness and analyticity for the solutions of the system. As consequences, exponential stability and impossibility of localization for the solutions are obtained.
Thu, 25 Apr 2019 10:14:26 GMT
http://hdl.handle.net/2117/131999
20190425T10:14:26Z
Bazarra, Noelia
Fernández, José Ramón
Leseduarte Milán, María Carme
Magaña Nieto, Antonio
Quintanilla de Latorre, Ramón
In this paper we analyze the system of equations that models the behaviour of materials with a double porous structure. We introduce dissipation mechanisms in both structures. We show existence, uniqueness and analyticity for the solutions of the system. As consequences, exponential stability and impossibility of localization for the solutions are obtained.