The Price of Civil Society

We study the inefficiency of equilibria for congestion games when players are (partially) altruistic. We model altruistic behavior by assuming that player i's perceived cost is a convex combination of 1 − α i times his direct cost and α i times the social cost. Tuning the parameters α i allows smooth interpolation between purely selfish and purely altruistic behavior. Within this framework, we study primarily altruistic extensions of (atomic and nonatomic) congestion games, but also obtain some results on fair cost-sharing games and valid utility games.We derive (tight) bounds on the price of anarchy of these games for several solution concepts. Thereto, we suitably adapt the smoothness notion introduced by Roughgarden and show that it captures the essential properties to determine the robust price of anarchy of these games. Our bounds show that for atomic congestion games and cost-sharing games, the robust price of anarchy gets worse with increasing altruism, while for valid utility games, it remains constant and is not affected by altruism.However, the increase in the price of anarchy is not a universal phenomenon: For general nonatomic congestion games with uniform altruism, the price of anarchy improves with increasing altruism. For atomic and nonatomic symmetric singleton congestion games, we derive bounds on the pure price of anarchy that improve as the average level of altruism increases. (For atomic games, we only derive such bounds when cost functions are linear.) Since the bounds are also strictly lower than the robust price of anarchy, these games exhibit natural examples in which pure Nash equilibria are more efficient than more permissive notions of equilibrium.

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“…For instance, such analyses are carried out in analyzing the price of anarchy and stability in Anshelevich et al [2012] and Buehler et al [2011].…”

Section: Subsequent Workmentioning

confidence: 99%

Altruism and Its Impact on the Price of Anarchy

Chen

Keijzer

Kempe

et al. 2014

ACM Trans. Econ. Comput.

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“…The friendship graph G F can be seen as a social context which dictates the benefits obtained by the nodes by playing a game on the connection graph G C . Some other work which explores different forms of social context are [10] and [20]. In this work, the cost of a node in a resource-sharing game depends on its own cost and the costs of its "friends", where friend nodes are its neighbors in an underlying social network.…”

Section: Related Work and Impact Of Two-hop Benefitmentioning

confidence: 99%

Friend of My Friend: Network Formation with Two-Hop Benefit

2014

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Abstract. How and why people form ties is a critical issue for understanding the fabric of social networks. In contrast to most existing work, we are interested in settings where agents are neither so myopic as to consider only the benefit they derive from their immediate neighbors, nor do they consider the effects on the entire network when forming connections. Instead, we consider games on networks where a node tries to maximize its utility taking into account the benefit it gets from the nodes it is directly connected to (called direct benefit), as well as the benefit it gets from the nodes it is acquainted with via a two-hop connection (called two-hop benefit). We call such games Two-Hop Games. The decision to consider only two hops stems from the observation that human agents rarely consider "contacts of a contact of a contact" (3-hop contacts) or further while forming their relationships. We consider several versions of Two-Hop games which are extensions of well-studied games. While the addition of two-hop benefit changes the properties of these games significantly, we prove that in many important cases good equilibrium solutions still exist, and bound the change in the price of anarchy due to two-hop benefit both theoretically and in simulation.

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“…Already for these simple models it has been observed in a series of papers [5,7,8] that altruistic behavior can actually be harmful in the sense that the price of anarchy may increase as players become more altruistic. This observation served as a starting point for the investigations conducted in this paper.…”

Section: Introductionmentioning

confidence: 99%

“…All these models are special cases of the one studied here. Among these articles, the inefficiency of equilibria in the presence of altruistic/spiteful behavior was studied for various games in [5,[7][8][9]14]. After its introduction in [22], the smoothness framework has been adapted in various directions [23][24][25], including an extension to a particular model of altruism in [8], which constitutes a special case of the altruistic games considered here.…”

Section: Introductionmentioning

confidence: 99%

Inefficiency of Games with Social Context

et al. 2015

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Abstract. The study of other-regarding player behavior such as altruism and spite in games has recently received quite some attention in the algorithmic game theory literature. Already for very simple models, it has been shown that altruistic behavior can actually be harmful for society in the sense that the price of anarchy may increase as the players become more altruistic. In this paper, we study the severity of this phenomenon for more realistic settings in which there is a complex underlying social structure, causing the players to direct their altruistic and spiteful behavior in a refined player-specific sense (depending, for example, on friendships that exist among the players). Our findings show that the increase in the price of anarchy is modest for congestion games and minsum scheduling games, whereas it is drastic for generalized second price auctions.

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The Price of Civil Society

Cited by 13 publications

References 20 publications

Altruism and Its Impact on the Price of Anarchy

Altruism and Its Impact on the Price of Anarchy

Friend of My Friend: Network Formation with Two-Hop Benefit

Inefficiency of Games with Social Context

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