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'''Organizers:''' [http://www.santafe.edu/~girvan/ Michelle Girvan] (University of Maryland) and [http://www.santafe.edu/~aaronc/ Aaron Clauset] (Santa Fe Institute)
 
'''Organizers:''' [http://www.santafe.edu/~girvan/ Michelle Girvan] (University of Maryland) and [http://www.santafe.edu/~aaronc/ Aaron Clauset] (Santa Fe Institute)
  
===Friday, January 12, 2008===
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===Friday, January 11, 2008===
  
3:10 - 3:50 '''Matthew O. Jackson''' ([http://www.stanford.edu/~jacksonm/ homepage])
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2:00 - 2:40 '''Michael Gastner''' ([http://www.santafe.edu/~mgastner/ homepage])
  
''An Economic Model of Friendships: Understanding the Roles of Choice and Chance in Social Network Formation''
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''The Price of Anarchy in Transportation Networks''
  
Both opportunity and preferences matter in social network formation. By examining an economic model of friendship formation that incorporates both choice in which relationships to form and chance meetings, we can sort out the relative roles of these two factors in determining social network structure. The model is used to understand three empirical patterns of friendship formation across different racial groups in U.S. high schools: (i) larger groups tend to form more same-race friendships and fewer cross-race friendships than small groups, (ii) larger groups form more friendships per capita, and (iii)  the most extreme bias towards own-race friendships is exhibited by middle-sized groups.  It is shown that these empirical observations can sorted according to whether they are driven by choice or chance.
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Uncoordinated individuals in human society pursuing their personally optimal strategies do not always achieve the social optimum, the most beneficial state to the society as a whole. Instead, strategies form Nash equilibria, which are, in general, socially suboptimal. Society, therefore, has to pay a price of anarchy for the lack of coordination among its members, which is often difficult to quantify in engineering, economics and policymaking. Here we report on an assessment of this price of anarchy by analyzing the road networks of Boston, London, and New York, where one's travel time serves as the relevant cost to be minimized. Our simulation shows that uncoordinated drivers possibly spend up to 30% more time than they would in socially optimal traffic, which leaves substantial room for improvement. Counterintuitively, simply blocking certain streets can partially improve the traffic condition to a measurable extent based on our result.

Latest revision as of 22:34, 3 January 2008

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Is There a Physics of Society? January 10-12, 2008, Santa Fe NM

Organizers: Michelle Girvan (University of Maryland) and Aaron Clauset (Santa Fe Institute)

Friday, January 11, 2008

2:00 - 2:40 Michael Gastner (homepage)

The Price of Anarchy in Transportation Networks

Uncoordinated individuals in human society pursuing their personally optimal strategies do not always achieve the social optimum, the most beneficial state to the society as a whole. Instead, strategies form Nash equilibria, which are, in general, socially suboptimal. Society, therefore, has to pay a price of anarchy for the lack of coordination among its members, which is often difficult to quantify in engineering, economics and policymaking. Here we report on an assessment of this price of anarchy by analyzing the road networks of Boston, London, and New York, where one's travel time serves as the relevant cost to be minimized. Our simulation shows that uncoordinated drivers possibly spend up to 30% more time than they would in socially optimal traffic, which leaves substantial room for improvement. Counterintuitively, simply blocking certain streets can partially improve the traffic condition to a measurable extent based on our result.