Discriminating by Tagging: Artificial Distinction, Real Discrimination

We introduce a new variation of the hawk-dove game suggested by an experiment that studies the behavior of a group of domestic fowls when a subgroup has been marked. Speci cally we consider a population formed by two types of individual that fail to recog- nize their own type but do recognize the other type. In this game we find two evolutionarily stable strategies. In each of them, individuals from one type are always attacked more, whatever proportion of the population they represent. Our theoretical results are consistent with the conclusions drawn from experimental work, where marked fowls received more pecks than their unmarked counterparts.

Admissible Hierachic Sets

In this paper we present a solution concept for abstract systems called the admissible hierarchic set. The solution we propose is a refinement of the hierarchic solution, a generalization of the von Neumann and Morgenstern solution. For finite abstract systems we show that the admissible hierarchic sets and the von Neumann and Morgenstern stable sets are the only outcomes of a coalition formation procedure (Wilson, 1972 and Roth, 1984). For coalitional games we prove that the core is either a vN&M stable set or an admissible hierarchic set.abstract system, coalitional game, corem, hierarchic solution, subsolution, Von Neumann and Morgenstern stable set

The Stability of the Roommate Problem Revisited

The lack of stability in some matching problems suggests that alternative solution concepts to the core might be applied to find predictable matchings. We propose the absorbing sets as a solution for the class of roommate problems with strict preferences. This solution, which always exists, either gives the matchings in the core or predicts some other matchings when the core is empty. Furthermore, it satisfies an interesting property of outer stability. We also characterize the absorbing sets, determine their number and, in case of multiplicity, we find that they all share a similar structure.roommate problem, core, absorbing sets

Discriminating by Tagging: Artificial Distinction, Real Discrimination

We introduce a new variation of the hawk-dove game suggested by an experiment that studies the behavior of a group of domestic fowls when a subgroup has been marked. Speci cally we consider a population formed by two types of individual that fail to recog- nize their own type but do recognize the other type. In this game we find two evolutionarily stable strategies. In each of them, individuals from one type are always attacked more, whatever proportion of the population they represent. Our theoretical results are consistent with the conclusions drawn from experimental work, where marked fowls received more pecks than their unmarked counterparts.This research is supported by the Spanish Ministerio de Ciencia e Innovación under projects SEJ2006-05455 and ECO2009-11213, co-funded by ERDF, and by Basque Government funding for Grupo Consolidado GIC07/146-IT-377-07. Elena Iñarra also gratefully acknowledges the hospitality of Oxford University and financial support from the Basque Goverment

Absorbing Sets in Coalitional Systems

The purpose of this paper is twofold: First, to present an approach and a solution for analyzing the stability of coalition structures: We define a coalitional system (a set and a binary relation on that set) that explains the transitions between coalition structures and we propose to solve these systems using the absorbing sets solution for abstract systems. Second, to perform an analysis of this approach to evidence its utility in determining the stable coalition structures for some socioeconomic problems. We find that the absorbing sets solution efficiently solves this class of coalitional systems.coalition structures, coalitional systems, absorbing sets solution

Rationing Rules and Stable Coalition Structures

Documento de trabajoWe consider a coalition formation model in which agents have the possibility of forming part of several coalitions but are limited to participate in only one of them. Coalitions of agents produce outputs to be distributed among their members according to their aspirations and to a rationing rule prevailing in society. The outcome of such a process is a hedonic game. Using monotonicity and consistency we characterize the continuous rationing rules that induce core-stable hedonic games.acknowledge nancial support from the Spanish Government ECO2015-67519-P and from the Basque Government IT568-1

Admissible Hierachic Sets

In this paper we present a solution concept for abstract systems called the admissible hierarchic set. The solution we propose is a refinement of the hierarchic solution, a generalization of the von Neumann and Morgenstern solution. For finite abstract systems we show that the admissible hierarchic sets and the von Neumann and Morgenstern stable sets are the only outcomes of a coalition formation procedure (Wilson, 1972 and Roth, 1984). For coalitional games we prove that the core is either a vN&M stable set or an admissible hierarchic set.Financial support from projects 9/UPV 00031.321-15352/2003, and MCYT BEC 2003-08182 is grateful acknowledged. E. Inarra acknowledges financial support from the Ministerio de Educación, Cultura y Deporte, PR 2003-0287

A noncooperative view on two consistent aiport cost sharing rules

This paper provides a noncooperative understanding of the nucleolus and the egalitarian allocation for airport cost problems. We find that every Nash equilibrium of the noncooperative game has the nucleolus as outcome while the egalitarian allocation is just one of the Nash outcomes.airport games, egalitarian allocation, nucleolus, Nash outcomes

The Stability of the Roommate Problem Revisited

The lack of stability in some matching problems suggests that alternative solution concepts to the core might be applied to find predictable matchings. We propose the absorbing sets as a solution for the class of roommate problems with strict preferences. This solution, which always exists, either gives the matchings in the core or predicts some other matchings when the core is empty. Furthermore, it satisfies an interesting property of outer stability. We also characterize the absorbing sets, determine their number and, in case of multiplicity, we find that they all share a similar structure.This research has been supported by the University of the Basque Country under project 1/UPV 00031.321-HA-7903/2000 and project GIU06/44 and by the Spanish Ministerio de Educación y Ciencia under project SEJ2006-05455, cofunded by FEDER and project BEC2000-0875. It has also benefited from the Franco-Spanish Exchange Program HF-2006-0021/EGIDE-Picasso

A new solution for the roommate problem: The Q-stable matchings

The aim of this paper is to propose a new solution for the roommate problem with strict preferences. We introduce the solution of maximum irreversibility and consider almost stable matchings (Abraham et al. [2])and maximum stable matchings (Ta [30] [32]). We find that almost stable matchings are incompatible with the other two solutions. Hence, to solve the roommate problem we propose matchings that lie at the intersection of the maximum irreversible matchings and maximum stable matchings, which are called Q-stable matchings. These matchings are core consistent and we offer an effi cient algorithm for computing one of them. The outcome of the algorithm belongs to an absorbing set.This research is supported by the Spanish Ministry of Science and Innovation (ECO2010- 17049 and ECO2012-31346), co-funded by ERDF, by Basque Government IT-568-13 and by the Government of Andalusia Project for Excellence in Research (P07.SEJ.02547). P eter Bir o also acknowledges the support from the Hungarian Academy of Sciences under its Momentum Programme (LD-004/2010), and the Hungarian Scientific Research Fund,OTKA, grant no.K108673