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 The Efficiency of Resource Allocation Mechanisms for Budget-Constrained Users

2020 ◽  
Author(s):  
Ioannis Caragiannis ◽  
Alexandros A. Voudouris
Keyword(s):  
Resource Allocation ◽  
Differential Equations ◽  
Social Welfare ◽  
Price Of Anarchy ◽  
Budget Constraint ◽  
Budget Constraints ◽  
Tight Bound ◽  
Worst Case ◽  
Seminal Work ◽  
The Social

We study the efficiency of mechanisms for allocating a divisible resource. Given scalar signals submitted by all users, such a mechanism decides the fraction of the resource that each user will receive and a payment that will be collected from her. Users are self-interested and aim to maximize their utility (defined as their value for the resource fraction they receive minus their payment). Starting with the seminal work of Johari and Tsitsiklis, a long list of papers studied the price of anarchy (in terms of the social welfare—the total users’ value) of resource allocation mechanisms for a variety of allocation and payment rules. Here, we further assume that each user has a budget constraint that invalidates strategies that yield a payment that is higher than the user’s budget. This subtle assumption, which is arguably more realistic, constitutes the traditional price of anarchy analysis meaningless as the set of equilibria may change drastically and their social welfare can be arbitrarily far from optimal. Instead, we study the price of anarchy using the liquid welfare benchmark that measures efficiency taking budget constraints into account. We show a tight bound of 2 on the liquid price of anarchy of the well-known Kelly mechanism and prove that this result is essentially best possible among all multiuser resource allocation mechanisms. This comes in sharp contrast to the no-budget setting where there are mechanisms that considerably outperform Kelly in terms of social welfare and even achieve full efficiency. In our proofs, we exploit the particular structure of worst-case games and equilibria, which also allows us to design (nearly) optimal two-player mechanisms by solving simple differential equations.

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 Favorite-Candidate Voting for Eliminating the Least Popular Candidate in a Metric Space

2020 ◽  
Vol 34 (02) ◽  
pp. 1894-1901
Author(s):  
Xujin Chen ◽  
Minming Li ◽  
Chenhao Wang
Keyword(s):  
Lower Bounds ◽  
Metric Space ◽  
Social Value ◽  
Upper And Lower Bounds ◽  
Worst Case ◽  
The Social ◽  
Special Cases ◽  
Worst Case Ratio ◽  
The One

We study single-candidate voting embedded in a metric space, where both voters and candidates are points in the space, and the distances between voters and candidates specify the voters' preferences over candidates. In the voting, each voter is asked to submit her favorite candidate. Given the collection of favorite candidates, a mechanism for eliminating the least popular candidate finds a committee containing all candidates but the one to be eliminated. Each committee is associated with a social value that is the sum of the costs (utilities) it imposes (provides) to the voters. We design mechanisms for finding a committee to optimize the social value. We measure the quality of a mechanism by its distortion, defined as the worst-case ratio between the social value of the committee found by the mechanism and the optimal one. We establish new upper and lower bounds on the distortion of mechanisms in this single-candidate voting, for both general metrics and well-motivated special cases.

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 Optimal Computer Crash Performance Precaution

2012 ◽  
Vol Vol. 14 no. 1 (Distributed Computing and...) ◽  
Author(s):  
Efraim Laksman ◽  
Hakan Lennerstad ◽  
Lars Lundberg
Keyword(s):  
Completion Time ◽  
Optimal Allocation ◽  
Parallel Program ◽  
Parallel Computer ◽  
Upper And Lower Bounds ◽  
Worst Case ◽  
Worst Case Ratio ◽  
International Audience ◽  
Computer Crash ◽  
The Cost

Distributed Computing and Networking International audience For a parallel computer system with m identical computers, we study optimal performance precaution for one possible computer crash. We want to calculate the cost of crash precaution in the case of no crash. We thus define a tolerance level r meaning that we only tolerate that the completion time of a parallel program after a crash is at most a factor r + 1 larger than if we use optimal allocation on m - 1 computers. This is an r-dependent restriction of the set of allocations of a program. Then, what is the worst-case ratio of the optimal r-dependent completion time in the case of no crash and the unrestricted optimal completion time of the same parallel program? We denote the maximal ratio of completion times f(r, m) - i.e., the ratio for worst-case programs. In the paper we establish upper and lower bounds of the worst-case cost function f (r, m) and characterize worst-case programs.

scholarly journals Hybrids Before Nonprofits: Key Challenges, Institutional Logics, and Normative Rules of Behavior of News Media Dedicated to Social Welfare

2020 ◽  
Vol 97 (3) ◽  
pp. 790-810
Author(s):  
Sergio Sparviero
Keyword(s):  
Social Welfare ◽  
News Media ◽  
Social Enterprise ◽  
Institutional Logics ◽  
Organizational Form ◽  
Institutional Logic ◽  
The Social ◽  
News Organizations ◽  
Social News ◽  
The Impact

This article proposes comparing nonprofit news organizations that prioritize social welfare goals with the hybrid organizational form that mixes the institutional logics of charities and business enterprises: the Social Enterprise. The institutional logic comprises organizing templates, patterns of actions and values. These Social News Enterprises (SNEs) are analyzed as hybrids mixing the institutional logics of commercial, public, and alternative news media. Financed by donations and the revenue from services, SNEs engage in public, investigative, and explanatory journalism. Normative behavioral principles of SNEs are used to compare the impact-based model of ProPublica with the growth-focused model of The Texas Tribune.

scholarly journals PERFORMANCE OF NON-COOPERATIVE ROUTING OVER PARALLEL NON-OBSERVABLE QUEUES

2016 ◽  
Vol 30 (3) ◽  
pp. 455-469 ◽  
Author(s):  
Olivier Brun
Keyword(s):  
Autonomic Computing ◽  
Price Of Anarchy ◽  
Service Discipline ◽  
Case Scenario ◽  
Selfish Behavior ◽  
Fixed Amount ◽  
Worst Case ◽  
Computer Services ◽  
The Mean ◽  
The Impact

Autonomic computing is emerging as a significant new approach to the design of computer services. Its goal is the development of services that are able to manage themselves with minimal direct human intervention, and, in particular, are able to sense their environment and to tune themselves to meet end-user needs. However, the impact on performance of the interaction between multiple uncoordinated self-optimizing services is not yet well understood. We present some recent results on a non-cooperative load-balancing game which help to better understand the result of this interaction. In this game, users generate jobs of different services, and the jobs have to be processed on one of the servers of a computing platform. Each service has its own dispatcher which probabilistically routes jobs to servers so as to minimize the mean processing cost of its own jobs. We first investigate the impact of heterogeneity in the amount of incoming traffic routed by dispatchers and present a result stating that, for a fixed amount of total incoming traffic, the worst-case overall performance occurs when each dispatcher routes the same amount of traffic. Using this result we then study the so-called Price of Anarchy (PoA), an oft-used worst-case measure of the inefficiency of non-cooperative decentralized architectures. We give explicit bounds on the PoA for cost functions representing the mean delay of jobs when the service discipline is PS or SRPT. These bounds indicate that significant performance degradations can result from the selfish behavior of self-optimizing services. In practice, though, the worst-case scenario may occur rarely, if at all. Some recent results suggest that for the game under consideration the PoA is an overly pessimistic measure that does not reflect the performance obtained in most instances of the problem.

America, Germany, Israel: Three Modes of Citizenship and Incorporation

2010 ◽  
Vol 78 (1) ◽  
pp. 123-128
Author(s):  
David Abraham
Keyword(s):  
United States ◽  
Welfare State ◽  
Social Welfare ◽  
The United States ◽  
Liberal Democracies ◽  
Social Community ◽  
Social Question ◽  
Free Mobility ◽  
The Social ◽  
The Impact

AbstractIn today's liberal democracies, the “social question” and the “immigration question” have become entwined as rarely before. Elites and citizens alike ask who belongs to the national political and social community of the “we” and what belonging entails in the way of rights and obligations. Under the impact of unprecedented free mobility for both capital and labor and the crises of the social welfare state, the borders and bonds of citizenship have been changing, mostly weakening. This essay takes a preliminary look at how these two questions are intertwined in the United States, Germany, and Israel.

Sign in / Sign up

Export Citation Format

Share Document