BUSCADOR RECOLECTA

In this paper we experimentally test Schelling’s (1971) segregation model and confirm the striking result of segregation. In addition, we extend Schelling’s model theoretically by adding strategic behaviour and moving costs. We obtain a unique subgame perfect equilibrium in which rational agents facing moving costs may find it optimal not to move (anticipating other participants’ movements). This equilibrium is far from full segregation. We run experiments for this extended Schelling model, and find that the percentage of full segregated societies notably decreases with the cost of moving and that the degree of segregation depends on the distribution of strategic subjects., Financial support from the Spanish Economy and Competitiveness Ministry (ECO2014-55745-R, ECO2013-46550-R, ECO2013-44879-R, SEJ-2012-1436, ECO2012-34202), Fundación BBVA, Junta de Andalucía Excelencia (P07-SEJ-02547) and Generalitat Valenciana (PROMETEOII/2014/054) is gratefully acknowledged.

In local social migrations, agents move from their initial location looking for a better local social environment. Social migrations processes do not change the number of social agents of a given type (i.e., the empirical distribution of the population) but their spatial location. Although cellular automata seems to appear as a natural approach to model of social migrations, the evolution of the configuration through a cellular automata might induce a new configuration wherein the number of agents of each type might be actually modified. This article provides a characterization of these cellular automata rules such that for any initial empirical distribution, the evolution of the configuration through a cellular automata of such class induces a new configuration with the same empirical distribution as the initial one, as required to model local social migrations. A class of sequences is defined in order to establish a sufficient condition to maintain this invariance property., Support from projects JC2009-00189 and MC238206 is also gratefully acknowledged. J. M. Benito-Ostolaza acknowledges financial support from Project ECO2009-12836 of the Ministry of Science and Innovation of Spain and Project ECO2012-34202 of Ministry of Economy and Competitivity of Spain. Likewise, P. Hernandez and J. Vila thank the Spanish Ministry of Science and Innovation and the European Feder Funds for financial support under project ECO2010-20584 and ECO2013-46550-R as well as the Prometeo Programme Funds PROMETEO/2009/068 and PROMETEOII/2013/019.

New systems can be designed, developed, and managed as societies of agents that interact
with each other by offering and providing services. These systems can be viewed as complex
networks where nodes are bounded rational agents. In order to deal with complex goals,
they require cooperation of the other agents to be able to locate the required services. The
aim of this paper is formally and empirically analyze under which circumstances cooperation
emerges in decentralized search of services. We propose a repeated game model that
formalizes the interactions among agents in a search process where agents are free to choose
between cooperate or not in the process. Agents make decisions based on the cost of their actions
and the expected reward if they participate forwarding queries in a search process that
ends successfully. We propose a strategy that is based on random-walks, and we study under
what conditions the strategy is a Nash equilibrium. We performed several experiments in order
to evaluate the model and the strategy and to analyze which network structures are more
appropriate to promote cooperation.
© 2015 Elsevier Inc. All rights reserved., This work is supported by SP2014800, TIN2011-27652-C03-01, TIN2012-36586-C03-01, PROMETEOII/2013/019 and by the Spanish Ministry of Science and Technology [Project ECO2013-46550-R and FEDER, PROMETEOII/2014/054].

We study minimum cost spanning tree problems for a set of users connected to a source. Prim’s algorithm provides a way of finding the minimum cost tree mm. This has led to several definitions in the literature, regarding how to distribute the cost. These rules propose different cost allocations, which can be understood as compensations and/or payments between players, with respect to the status quo point: each user pays for the connection she uses to be linked to the source. In this paper we analyze the rationale behind a distribution of the minimum cost by defining an a priori transfer structure. Our first result states the existence of a transfer structure such that no user is willing to choose a different tree from the minimum cost tree. Moreover, given a transfer structure, we implement the above solution as a subgame perfect equilibrium outcome of a game where players decide sequentially with whom to connect. Finally, we obtain that the existence of a transfer structure supporting an allocation characterizes the core of the monotone cooperative game associated with a minimum cost spanning tree problem. This transfer structure is called social transfer structure. Therefore, the minimum cost spanning tree emerges as both a social and individual solution., Hernández would like to thank MEC Spain (ECO2013-46550-R) for their financial support and she gratefully acknowledges the Generalitat Valenciana (PROMETEO/2009/068). Silva would like to thank the Generalitat Valenciana (PROMETEO/2009/068) and Peris and Silva gratefully acknowledge financial support from Spanish Ministry of Economy and Competitiveness under Project ECO2013-43119-P.