Search results for "Opera"
showing 10 items of 8665 documents
Characterizing and Quantifying Frustration in Quantum Many-Body Systems
2011
We present a general scheme for the study of frustration in quantum systems. We introduce a universal measure of frustration for arbitrary quantum systems and we relate it to a class of entanglement monotones via an exact inequality. If all the (pure) ground states of a given Hamiltonian saturate the inequality, then the system is said to be inequality saturating. We introduce sufficient conditions for a quantum spin system to be inequality saturating and confirm them with extensive numerical tests. These conditions provide a generalization to the quantum domain of the Toulouse criteria for classical frustration-free systems. The models satisfying these conditions can be reasonably identifi…
Fixed Point Theorems with Applications to the Solvability of Operator Equations and Inclusions on Function Spaces
2015
Fixed point theory is an elegant mathematical theory which is a beautiful mixture of analysis, topology, and geometry. It is an interdisciplinary theory which provides powerful tools for the solvability of central problems in many areas of current interest in mathematics and other quantitative sciences, such as physics, engineering, biology, and economy. In fact, the existence of linear and nonlinear problems is frequently transformed into fixed point problems, for example, the existence of solutions to partial differential equations, the existence of solutions to integral equations, and the existence of periodic orbits in dynamical systems. This makes fixed point theory a topical area and …
Cross-border integration of universities as a possible research topic in border studies
2021
The text deals with the cross-border cooperation of universities as a possible new research topic in border studies. We identified two important associations of universities operating in border areas in the EU core and two associations gathering universities from Czech, Polish and Slovak areas. Then we tried to identify the areas in which these universities cooperate. It turned out that the principal difference is in a significantly higher number of joint study programs. This has probably a link to the high cross-border integration in the EU core. We believe that the topic is promising and deserves much higher attention, as it probably points at new and not really exploited cross-border int…
Spherical harmonic expansion of fundamental solutions and their derivatives for homogenous elliptic operators
2017
In this work, a unified scheme for computing the fundamental solutions of a three-dimensional homogeneous elliptic partial differential operator is presented. The scheme is based on the Rayleigh expansion and on the Fourier representation of a homogeneous function. The scheme has the advantage of expressing the fundamental solutions and their derivatives up to the desired order without any term-by-term differentiation. Moreover, the coefficients of the series need to be computed only once, thus making the presented scheme attractive for numerical implementation. The scheme is employed to compute the fundamental solution of isotropic elasticity showing that the spherical harmonics expansions…
La caída de las cajas de ahorros españolas. Cuestión de rentabilidad, tamaño y estructura de propiedad=The Fall of Spanish Savings Banks. Question of…
2012
En España entre 2010 y 2011 se ha producido una gran restructuración financiera, que ha llevado a la práctica desa-parición de las Cajas de Ahorros mediante fusiones y posterior cambio de estructura de la propiedad convirtiéndose en bancos. Esta gran restructuración ha sido promovida por el Banco de España, como salida para que las entidades financieras subsistieran a la crisis que les afectaba. Este trabajo analiza los bancos y cajas del sistema financiero español durante los cuatro años previos al comienzo de la reestructuración financiera del 2010. El objetivo es comprobar si existen diferencias en cuanto a rentabilidad por causas de tamaño y tipo de gobierno de la entidad (cajas de ahor…
deaR-Shiny: An Interactive Web App for Data Envelopment Analysis
2021
In this paper, we describe an interactive web application (deaR-shiny) to measure efficiency and productivity using data envelopment analysis (DEA). deaR-shiny aims to fill the gap that currently exists in the availability of online DEA software offering practitioners and researchers free access to a very wide variety of DEA models (both conventional and fuzzy models). We illustrate how to use the web app by replicating the main results obtained by Carlucci, Cirà and Coccorese in 2018, who investigate the efficiency and economic sustainability of Italian regional airport by using two conventional DEA models, and the results given by Kao and Liu in their papers published in 2000 and 2003, wh…
A Logic Fuzzy Model for Evaluation of the Railway Station’s Practice Capacity in Safety Operating Conditions
2013
Abstract The practice capacity of a railway junction depends, in addition to the effective operation’s conditions, by the potential risk factors related to the design plan of the railway station. With the aim of an approach based on the “fuzzy sets” it is possible to determine the numeric value of the practice capacity by the logic - qualitative relations between the features of the railway junction and the potential risk factors. This methodology permits to try out the absolute value of a suitable vector β, (less then the unit) for the utilization of the theoretic capacity in conditions of maximum reliability of the system related to the aspect of safety (technique “fail safe”).
Punishment and efficiency: theoretical and experimental approaches
2018
Los dilemas sociales se caracterizan por la desalineación de incentivos privados y sociales bajo preferencias egoístas. Mientras el óptimo social se alcanza mediante la implementación de un conjunto particular de acciones, los incentivos individuales mueven a los agentes a comportarse de una manera diferente, lo cual lleva a resultados ineficientes. Un ejemplo clásico es la provisión de un bien público, donde el óptimo se alcanza si todos contribuyen, sin embargo hay una desviación unilateral provechosa a hacer de polizón, es decir, a no contribuir al bien público y beneficiarse de los demás. De este modo, dar a los agentes egoístas la posibilidad de elegir libremente sus asignaciones lleva…
A non-cooperative approach to the folk rule in minimum cost spanning tree problems
2023
This paper deals with the problem of finding a way to distribute the cost of a minimum cost spanning tree problem between the players. A rule that assigns a payoff to each player provides this distribution. An optimistic point of view is considered to devise a cooperative game. Following this optimistic approach, a sequential game provides this construction to define the action sets of the players. The main result states the existence of a unique cost allocation in subgame perfect equilibria. This cost allocation matches the one suggested by the folk rule. The authors thank the support of the Spanish Ministry of Science, Innovation and Universities, the Spanish Ministry of Economy and Compe…
Density flow over networks: A mean-field game theoretic approach
2014
A distributed routing control algorithm for dynamic networks has recently been presented in the literature. The networks were modeled using time evolution of density at network edges and the routing control algorithm allowed edge density to converge to a Wardrop equilibrium, which was characterized by an equal traffic density on all used paths. We borrow the idea and rearrange the density model to recast the problem within the framework of mean-field games. The contribution of this paper is three-fold. First, we provide a mean-field game formulation of the problem at hand. Second, we illustrate an extended state space solution approach. Third, we study the stochastic case where the density …