scholarly journals Selfishness Level of Strategic Games

2014 ◽  
Vol 49 ◽  
pp. 207-240 ◽  
Author(s):  
K. R. Apt ◽  
G. Schaefer
Keyword(s):  
Nash Equilibrium ◽  
Social Welfare ◽  
Price Of Anarchy ◽  
Congestion Games ◽  
Price Of Stability ◽  
Social Optimum ◽  
Potential Game ◽  
Strategic Games ◽  
The Social ◽  
The Impact

We introduce a new measure of the discrepancy in strategic games between the social welfare in a Nash equilibrium and in a social optimum, that we call selfishness level. It is the smallest fraction of the social welfare that needs to be offered to each player to achieve that a social optimum is realized in a pure Nash equilibrium. The selfishness level is unrelated to the price of stability and the price of anarchy and is invariant under positive linear transformations of the payoff functions. Also, it naturally applies to other solution concepts and other forms of games. We study the selfishness level of several well-known strategic games. This allows us to quantify the implicit tension within a game between players' individual interests and the impact of their decisions on the society as a whole. Our analyses reveal that the selfishness level often provides a deeper understanding of the characteristics of the underlying game that influence the players' willingness to cooperate. In particular, the selfishness level of finite ordinal potential games is finite, while that of weakly acyclic games can be infinite. We derive explicit bounds on the selfishness level of fair cost sharing games and linear congestion games, which depend on specific parameters of the underlying game but are independent of the number of players. Further, we show that the selfishness level of the $n$-players Prisoner's Dilemma is c/(b(n-1)-c), where b and c are the benefit and cost for cooperation, respectively, that of the n-players public goods game is (1-c/n)/(c-1), where c is the public good multiplier, and that of the Traveler's Dilemma game is (b-1)/2, where b is the bonus. Finally, the selfishness level of Cournot competition (an example of an infinite ordinal potential game), Tragedy of the Commons, and Bertrand competition is infinite.

scholarly journals The Impact of Selfishness in Hypergraph Hedonic Games

2020 ◽  
Vol 34 (02) ◽  
pp. 1766-1773
Author(s):  
Alessandro Aloisio ◽  
Michele Flammini ◽  
Cosimo Vinci
Keyword(s):  
Social Welfare ◽  
Price Of Anarchy ◽  
Maximum Size ◽  
Upper And Lower Bounds ◽  
Worst Case ◽  
The Social ◽  
Worst Case Ratio ◽  
Distinct Node ◽  
Hedonic Games ◽  
The Impact

We consider a class of coalition formation games that can be succinctly represented by means of hypergraphs and properly generalizes symmetric additively separable hedonic games. More precisely, an instance of hypegraph hedonic game consists of a weighted hypergraph, in which each agent is associated to a distinct node and her utility for being in a given coalition is equal to the sum of the weights of all the hyperedges included in the coalition. We study the performance of stable outcomes in such games, investigating the degradation of their social welfare under two different metrics, the k-Nash price of anarchy and k-core price of anarchy, where k is the maximum size of a deviating coalition. Such prices are defined as the worst-case ratio between the optimal social welfare and the social welfare obtained when the agents reach an outcome satisfying the respective stability criteria. We provide asymptotically tight upper and lower bounds on the values of these metrics for several classes of hypergraph hedonic games, parametrized according to the integer k, the hypergraph arity r and the number of agents n. Furthermore, we show that the problem of computing the exact value of such prices for a given instance is computationally hard, even in case of non-negative hyperedge weights.

scholarly journals On Non-Cooperativeness in Social Distance Games

2019 ◽  
Vol 66 ◽  
pp. 625-653
Author(s):  
Alkida Balliu ◽  
Michele Flammini ◽  
Giovanna Melideo ◽  
Dennis Olivetti
Keyword(s):  
Nash Equilibrium ◽  
Polynomial Time ◽  
Social Distance ◽  
Price Of Anarchy ◽  
Cluster Formation ◽  
Solution Concept ◽  
Price Of Stability ◽  
The Social ◽  
Np Complete ◽  
Inverse Distance

We consider Social Distance Games (SDGs), that is cluster formation games in which the utility of each agent only depends on the composition of the cluster she belongs to, proportionally to her harmonic centrality, i.e., to the average inverse distance from the other agents in the cluster. Under a non-cooperative perspective, we adopt Nash stable outcomes, in which no agent can improve her utility by unilaterally changing her coalition, as the target solution concept. Although a Nash equilibrium for a SDG can always be computed in polynomial time, we obtain a negative result concerning the game convergence and we prove that computing a Nash equilibrium that maximizes the social welfare is NP-hard by a polynomial time reduction from the NP-complete Restricted Exact Cover by 3-Sets problem. We then focus on the performance of Nash equilibria and provide matching upper bound and lower bounds on the price of anarchy of Θ(n), where n is the number of nodes of the underlying graph. Moreover, we show that there exists a class of SDGs having a lower bound on the price of stability of 6/5 − ε, for any ε > 0. Finally, we characterize the price of stability 5 of SDGs for graphs with girth 4 and girth at least 5, the girth being the length of the shortest cycle in the graph.

London's Congestion Charge

2017 ◽  
pp. 1-10
Author(s):  
David Besanko ◽  
Johannes Horner ◽  
Ed Kalletta
Keyword(s):  
Social Welfare ◽  
Traffic Congestion ◽  
Social Optimum ◽  
Deadweight Loss ◽  
Sufficient Data ◽  
Negative Externalities ◽  
General Terms ◽  
Congestion Charge ◽  
The Social

Describes the events leading up to the imposition of the London congestion charge. Views about the congestion charge, both pro and con, are presented. Also discusses, in general terms, the economics of traffic congestion, pointing out that an unregulated market for driving will not reach the social optimum. Contains sufficient data to estimate the deadweight loss in an unregulated market and the reduction of the deadweight loss due to the imposition of the congestion charge in 2003.To provide a good illustration of how an unregulated market with negative externalities can lead to an overprovision of a good (in this case driving). Also, to show how an externality tax (in this case, London's congestion charge) can lead to an improvement in social welfare.

Empirical Models of Lobbying

2020 ◽  
Vol 12 (1) ◽  
pp. 391-413 ◽  
Author(s):  
Matilde Bombardini ◽  
Francesco Trebbi
Keyword(s):  
Political Economy ◽  
Welfare Effects ◽  
Empirical Models ◽  
Empirical Literature ◽  
Social Optimum ◽  
Methodological Issues ◽  
Open Questions ◽  
The Social ◽  
Special Interest Politics ◽  
The Impact

This article offers a review of the recent empirical literature on lobbying within political economy. In surveying extant research, we emphasize quid pro quo and informational issues in special interest politics and highlight crucial open questions in both. The two main unresolved methodological issues remain ( a) how to account for the impact of lobbying on which equilibrium policies are chosen and advanced and ( b) how distorted those equilibrium policies are relative to the social optimum. Of the principal open questions within political economy, a comprehensive, quantitative assessment of the welfare effects of lobbying remains one of the most elusive.

scholarly journals Social Learning with Costly Search

2016 ◽  
Vol 8 (1) ◽  
pp. 83-109 ◽  
Author(s):  
Manuel Mueller-Frank ◽  
Mallesh M. Pai
Keyword(s):  
Social Learning ◽  
Social Welfare ◽  
Discount Rate ◽  
Learning Model ◽  
Search Costs ◽  
Social Optimum ◽  
Linear Rate ◽  
The Social

We study a sequential social learning model where agents privately acquire information by costly search. Search costs of agents are private, and are independently and identically distributed. We show that asymptotic learning occurs if and only if search costs are not bounded away from zero. We explicitly characterize equilibria for the case of two actions, and show that the probability of late moving agents taking the suboptimal action vanishes at a linear rate. Social welfare converges to the social optimum as the discount rate converges to one if and only if search costs are not bounded away from zero. (JEL D81, D83)

THE PRICE OF NASH EQUILIBRIA IN MULTICAST TRANSMISSION GAMES

2010 ◽  
Vol 11 (03n04) ◽  
pp. 97-120 ◽  
Author(s):  
VITTORIO BILÒ
Keyword(s):  
Nash Equilibrium ◽  
Cost Sharing ◽  
Price Of Anarchy ◽  
Optimal Solution ◽  
Minimum Cost ◽  
Price Of Stability ◽  
Common Source ◽  
Cost Share ◽  
Worst Case ◽  
The Cost

We consider the problem of sharing the cost of multicast transmissions in non-cooperative undirected networks where a set of receivers R wants to be connected to a common source s. The set of choices available to each receiver r ∈ R is represented by the set of all (s, r)-paths in the network. Given the choices performed by all the receivers, a public known cost sharing method determines the cost share to be charged to each of them. Receivers are selfish agents aiming to obtain the transmission at the minimum cost share and their interactions create a non-cooperative game. Devising cost sharing methods yielding games whose price of anarchy (price of stability), defined as the worst-case (best-case) ratio between the cost of a Nash equilibrium and that of an optimal solution, is not too high is thus of fundamental importance in non-cooperative network design. Moreover, since cost sharing games naturally arise in socio-economical contests, it is convenient for a cost sharing method to meet some constraining properties. In this paper, we first define several such properties and analyze their impact on the prices of anarchy and stability. We also reconsider all the methods known so far by classifying them according to which properties they satisfy and giving the first non-trivial lower bounds on their price of stability. Finally, we propose a new method, namely the free-riders method, which admits a polynomial time algorithm for computing a pure Nash equilibrium whose cost is at most twice the optimal one. Some of the ideas characterizing our approach have been independently proposed in Ref. 10.

Conceptualizing the Social Economy in China

2012 ◽  
Vol 47 (3) ◽  
pp. 1083-1123 ◽  
Author(s):  
LI ZHAO
Keyword(s):  
Social Welfare ◽  
Political Institutions ◽  
Poverty Reduction ◽  
Social Economy ◽  
Welfare System ◽  
Cultural Traditions ◽  
For Profit ◽  
Social Welfare System ◽  
The Social ◽  
The Impact

AbstractThis study offers a conceptual analysis of the social economy in China within the context of institutional transition. In China, economic reform has engendered significant social changes. Accelerated economic growth, privatization of the social welfare system, and the rise of civil society explain the institutional contexts in which a range of not-for-profit initiatives, neither state-owned nor capital-driven, re-emerged. They are defined in this research as the social economy in China. This study shows that although the term itself is quite new, the social economy is no new phenomenon in China, as its various elements have a rich historical tradition. Moreover, the impact of the transition on the upsurge of the Chinese social economy is felt not only through direct means of de-nationalization and marketization and, as a consequence, the privatization of China's social welfare system, but also through various indirect means. The development of the social economy in China was greatly influenced by the framework set by political institutions and, accordingly, legal enabling environments. In addition, the link to the West, as well as local historical and cultural traditions, contribute towards explaining its re-emergence. Examining the practices in the field shows that the social economy sector in China is conducive to achieving a plural economy and an inclusive society, particularly by way of poverty reduction, social service provision, work integration, and community development. Therefore, in contemporary China, it serves as a key sector for improving welfare, encouraging participation, and consolidating solidarity.

International Social Work and Social Welfare: Central America

2013 ◽  
Author(s):  
Maria Julia
Keyword(s):  
Social Work ◽  
Social Welfare ◽  
Central America ◽  
International Social Work ◽  
Political Processes ◽  
New Approaches ◽  
Political Events ◽  
The Social ◽  
The Impact ◽  
International Social

The social, political, and economic features of Central America are summarized and the impact of economic and political processes on the region is highlighted. Predominant global, historical, cultural, and political events are weaved together, in an attempt to understand the realities of the region. The challenges for social work profession and practice are presented, as well as their implications for new approaches to intervention and education.

scholarly journals The price of anarchy in routing games as a function of the demand

2021 ◽  
Author(s):  
Roberto Cominetti ◽  
Valerio Dose ◽  
Marco Scarsini
Keyword(s):  
Price Of Anarchy ◽  
Heavy Traffic ◽  
Scaling Law ◽  
Congestion Games ◽  
Social Optimum ◽  
Asymptotic Results ◽  
Worst Case ◽  
Traffic Demand ◽  
Break Points ◽  
Routing Games

AbstractThe price of anarchy has become a standard measure of the efficiency of equilibria in games. Most of the literature in this area has focused on establishing worst-case bounds for specific classes of games, such as routing games or more general congestion games. Recently, the price of anarchy in routing games has been studied as a function of the traffic demand, providing asymptotic results in light and heavy traffic. The aim of this paper is to study the price of anarchy in nonatomic routing games in the intermediate region of the demand. To achieve this goal, we begin by establishing some smoothness properties of Wardrop equilibria and social optima for general smooth costs. In the case of affine costs we show that the equilibrium is piecewise linear, with break points at the demand levels at which the set of active paths changes. We prove that the number of such break points is finite, although it can be exponential in the size of the network. Exploiting a scaling law between the equilibrium and the social optimum, we derive a similar behavior for the optimal flows. We then prove that in any interval between break points the price of anarchy is smooth and it is either monotone (decreasing or increasing) over the full interval, or it decreases up to a certain minimum point in the interior of the interval and increases afterwards. We deduce that for affine costs the maximum of the price of anarchy can only occur at the break points. For general costs we provide counterexamples showing that the set of break points is not always finite.

Sign in / Sign up

Export Citation Format

Share Document