Universal Abelian topological groups

A topological group G is said to be universal in a class K of topological groups if G is an element of K and if for every group H is an element of K there is a subgroup K of G that is isomorphic to H as a topological group. A group is constructed that is universal in the class of separable metrizable topological Abelian groups.

Analysing orchestrations with risk profiles and angel-daemon games

In this paper game theory is used to analyse the effect of a number of service failures during the execution of a grid orchestration. A service failure may be catastrophic in that it causes an entire orchestration to fail. Alternatively, a grid manager may utilise alternative services in the case of failure, allowing an orchestration to recover, A risk profile provides a means of modelling situations in a way that is neither overly optimistic nor overly pessimistic. Risk profiles are analysed using angel and daemon games. A risk profile can be assigned a valuation through an analysis of the structure of its associated Nash equilibria. Some structural properties of valuation functions, that show their validity as a measure for risk, are given. Two main cases are considered, the assessment of Orc expressions and the arrangement of a meeting using reputations.

The influence of video games with apocalyptic content in adolescents

The aim of this study is the dissertation and analysis of the influence (sociological, psychological and cultural) exerted on adolescents by the concept of Apocalypse. Become a key thought of visual culture, the called doomsday theory achieves one of its highest expressions in video games, possibly the favorite entertainment for young people in their leisure time. The results obtained in this research represent a first approach to the subject through the selected samples, two secondary schools from the city of Seville with disparate locations and divergent socioeconomic backgrounds. To reinforce the comparative study, we have included issues related to parental control, principal gaming platforms used by respondents or the number of hours dedicated to this type of entertainment. The conclusions demonstrate an irremediable attraction from our youth towards apocalyptic universes, plotter consciously with leisure and entertainment as escape from their routine of everyday life.

A bargaining set for monotonic simple games based on external and internal stability

A new bargaining set based on notions of both internal and external stability is developed in the context of endogenous coalition formation. It allows to make an explicit distinction between within-group and outside-group deviation options. This type of distinction is not present in current bargaining sets. For the class of monotonic proper simple games, the outcomes in the bargaining set are characterized. Furthermore, it is shown that the bargaining set of any homogeneous weighted majority game contains an outcome for which the underlying coalition structure consists of a minimal winning coalition and its complement.

Coalitional Games and Contracts Based on Individual Deviations

We study what coalitions form and how the members of each coalition split the coalition value in coalitional games in which only individual deviations are allowed. In this context we employ three stability notions: individual, contractual, and compensational stability. These notions differ in terms of the underlying contractual assumptions. We characterize the coalitional games in which individually stable outcomes exist by means of the top-partition property. Furthermore, we show that any coalition structure of maximum social worth is both contractually and compensationally stable.