Social Network Formation with Consent

We investigate the equilibria of game theoretic models of network formation that are based on individual actions only.Our approach is grounded in three simple and realistic principles: (1) Link formation should be a binary process of consent.(2) Link formation should be costly.(3) The class of network payoff functions should be as general as possible.It is accepted that these consent models have a very large number of equilibria.However, until now no characterization of these equilibria has been established in the literature.We aim to fill this void and provide characterizations of stable networks or the cases of two-sided and one-sided link formation costs.Furthermore, we provide a comparison of Nash equilibria with potential maximizers for a certain specification.game theory;general equilibrium

The Role of Trust in Costly Network Formation

We consider game theoretic models of social network formation.In this paper we limit our investigation to game theoretic models of network formation that are based on individual actions only.Our approach is based on three simple and realistic principles: (1) Link formation is a binary process of consent.(2) Link formation is costly.(3) The class of network payo functions should be as general as possible.We provide characterizations of stable networks under the hypothesis of mutual consent in the cases of two-sided and one-sided link formation costs. Furthermore, we introduce a new equilibrium concept based on a limited, realistic form of farsightedness or "trust" in network formation.game theory;models;general equilibrium;stability

Stable Networks and Convex Payoffs

Recently a variety of link-based stability concepts have emerged in the literature on game theoretic models of social network formation.We investigate two basic formation properties that establish equivalence between some well known types of stable networks and their natural extensions.These properties can be identified as convexity conditions on the network payoff structures.social networks;network formation;pairwise stability

A note on the decentralization of Pareto optima in economies with public projects and nonessential private goods

Welfare Economics;Public Goods

The Role of Middlemen inEfficient and Strongly Pairwise Stable Networks

We examine the strong pairwise stability concept in network formation theory under collective network benefits.Strong pairwise stability considers a pair of players to add a link through mutual consent while permitting them to unilaterally delete any subset of links under their control.We examine the properties of strongly pairwise stable networks and find that players in middleman positions, who have the power to break up the network into multiple components, play a critical role in such networks.We show that for the component-wise egalitarian rule there is no conflict between the efficient and stable networks when these middlemen have no incentive to break up the network. Finally, we examine efficiency and stability in middleman-free networks.networks;stability

Coalition formation in large network economies

Organizational Structure;economic networks

Non-Langevin behaviour of the uncompensated magnetisation in nanoparticles of artificial ferritin

The magnetic behaviour of nanoparticles of antiferromagnetic ferritin has been investigated by 57Fe Mossbauer absorption spectroscopy and magnetisation measurements, in the temperature range 2.5K-250K and with magnetic fields up to 7T. Samples containing nanoparticles with an average number of Fe atoms ranging from 400 to 2500 were studied. The value of the anisotropy energy per unit volume was determined and found to be in the range 3-6 10**5 ergs/cm3, which is a value typical for ferric oxides. By comparing the results of the two experimental methods at large field, we show that, contratry to what is currently assumed, the uncompensated magnetisation of the feritin cores in the superparamagnetic regime does not follow a Langevin law. For magnetic fields below the spin-flop field, we propose an approximate law for the field and temperature variation of the uncompensated magnetisation which has so far never been applied in antiferromagnetic systems. This approach should more generally hold for randomly oriented antiferro- magnetic nanoparticles systems with weak uncompensated moments.Comment: 11 pages, 11 figure