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TZID:Europe/Paris
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BEGIN:VEVENT
UID:1-52@lptms.universite-paris-saclay.fr
DTSTART:20120614T143000Z
DTEND:20120614T153000Z
DTSTAMP:20120521T075639Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-de-la-f
 ederation-phsystat-sud-matteo-marsili/
SUMMARY:Séminaire de la Fédération PHSYSTAT-SUD : Matteo Marsili - LPTMS
 \, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay - 14 Juin 12 14:30
DESCRIPTION:Collaboration in social networks\nMatteo Marsili ( The Abdus Sa
 lam International Center for Theoretical Physics\, Trieste)\nThe very noti
 on of social network implies that linked individuals interact repeatedly w
 ith each other. This notion allows them not only to learn successful strat
 egies and adapt to them\, but also to condition their own behavior on the 
 behavior of others\, in a strategic forward looking manner. Game theory of
  repeated games shows that these circumstances are conducive to the emerge
 nce of collaboration in simple games of two players. We investigate the ex
 tension of this concept to the case where players are engaged in a local c
 ontribution game and show that rationality and credibility of threats iden
 tify a class of Nash equilibria—that we call “collaborative equilibria
 ”—that have a precise interpretation in terms of subgraphs of the soci
 al network. For large network games\, the number of such equilibria is exp
 onentially large in the number of players. When incentives to defect are s
 mall\, equilibria are supported by local structures whereas when incentive
 s exceed a threshold they acquire a nonlocal nature\, which requires a “
 critical mass” of more than a given fraction of the players to collabora
 te. Therefore\, when incentives are high\, an individual deviation typical
 ly causes the collapse of collaboration across the whole system. At the sa
 me time\, higher incentives to defect typically support equilibria with a 
 higher density of collaborators. The resulting picture conforms with sever
 al results in sociology and in the experimental literature on game theory\
 , such as the prevalence of collaboration in denser groups and in the stru
 ctural hubs of sparse networks.\n&nbsp\;
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 
 Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
 me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
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