scholarly journals A GENERIC APPROACH TO COALITION FORMATION

2009 ◽  
Vol 11 (03) ◽  
pp. 347-367 ◽  
Author(s):  
KRZYSZTOF R. APT ◽  
ANDREAS WITZEL
Keyword(s):  
Coalition Formation ◽  
Preference Relation ◽  
Exchange Economy ◽  
Conceptual Tool ◽  
Tu Games ◽  
Abstract Approach ◽  
Stable Partition ◽  
Hedonic Games

We propose an abstract approach to coalition formation that focuses on simple merge and split rules transforming partitions of a group of players. We identify conditions under which every iteration of these rules yields a unique partition. The main conceptual tool is a specific notion of a stable partition. The results are parametrized by a preference relation between partitions of a group of players and naturally apply to coalitional TU-games, hedonic games and exchange economy games.

scholarly journals A Coalition Formation Game Approach for Efficient Cooperative Multi-UAV Deployment

2018 ◽  
Author(s):  
Lang Ruan ◽  
Jin Chen ◽  
Qiuju Guo ◽  
Han Jiang ◽  
Yuli Zhang ◽  
...  
Keyword(s):  
Coalition Formation ◽  
Data Transmission ◽  
Cooperative Control ◽  
Base Station ◽  
Transmission Mechanism ◽  
Coalition Formation Game ◽  
Stable Partition ◽  
Considerable Benefit ◽  
Formation Game ◽  
Multi Uav

UAV cooperative control has been an important issue in UAV-assisted sensor network, thanks to the considerable benefit obtained from cooperative mechanism of UAVs being applied as a flying base station. In coverage scenario, the tradeoff between coverage performance and transmission performance often makes deployment of UAVs fall into a dilemma, since both indexes are related to the distance between UAVs. To address this issue, UAV coverage and data transmission mechanism is analyzed in this paper, then an efficient multi-UAV cooperative deployment model is proposed. The problem is also modeled as a coalition formation game (CFG). The CFG with Pareto order is proved to have a stable partition. Then, an effective approach consisting of coverage deployment and coalition selection is designed, wherein UAVs can decide strategies cooperatively to achieve better coverage performance. Combining analysis of game approach, a coalition selection and position deployment algorithm based on Pareto order (CSPDA-PO) is designed to execute coverage deployment and coalition selection. Finally, simulation results are shown to validate the proposed approach based on efficient multi-UAV cooperative deployment model.

scholarly journals Altruism in Coalition Formation Games

2020 ◽  
Author(s):  
Anna Maria Kerkmann ◽  
Jörg Rothe
Keyword(s):  
Coalition Formation ◽  
Computational Analysis ◽  
Altruistic Behavior ◽  
Major Disadvantage ◽  
Hedonic Games ◽  
Stability Notions

Nguyen et al. [2016] introduced altruistic hedonic games in which agents’ utilities depend not only on their own preferences but also on those of their friends in the same coalition. We propose to extend their model to coalition formation games in general, considering also the friends in other coalitions. Comparing the two models, we argue that excluding some friends from the altruistic behavior of an agent is a major disadvantage that comes with the restriction to hedonic games. After introducing our model, we additionally study some common stability notions and provide a computational analysis of the associated verification and existence problems.

scholarly journals Stable and Envy-free Partitions in Hedonic Games

2019 ◽  
Author(s):  
Nathanaël Barrot ◽  
Makoto Yokoo
Keyword(s):  
Coalition Formation ◽  
Grand Coalition ◽  
Core Stability ◽  
Pareto Optimal ◽  
Hedonic Games ◽  
Np Complete ◽  
Stability Notions

In this paper, we study coalition formation in hedonic games through the fairness criterion of envy-freeness. Since the grand coalition is always envy-free, we focus on the conjunction of envy-freeness with stability notions. We first show that, in symmetric and additively separable hedonic games, an individually stable and justified envy-free partition may not exist and deciding its existence is NP-complete. Then, we prove that the top responsiveness property guarantees the existence of a Pareto optimal, individually stable, and envy-free partition, but it is not sufficient for the conjunction of core stability and envy-freeness. Finally, under bottom responsiveness, we show that deciding the existence of an individually stable and envy-free partition is NP-complete, but a Pareto optimal and justified envy-free partition always exists.

scholarly journals Subordinated Hedonic Games

Game Theory ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
Juan Carlos Cesco
Keyword(s):  
Coalition Formation ◽  
Existence Result ◽  
Solution Concept ◽  
Stable Matching ◽  
Existence Problem ◽  
New Class ◽  
The Core ◽  
Reduced Game ◽  
Marriage Model ◽  
Hedonic Games

Hedonic games are simple models of coalition formation whose main solution concept is that of core partition. Several conditions guaranteeing the existence of core partitions have been proposed so far. In this paper, we explore hedonic games where a reduced family of coalitions determines the development of the game. We allow each coalition to select a subset of it so as to act as its set of representatives (a distribution). Then, we introduce the notion of subordination of a hedonic game to a given distribution. Subordination roughly states that any player chosen as a representative for a coalition has to be comfortable with this decision. With subordination we have a tool, within hedonic games, to compare how a “convenient” agreement reached by the sets of representatives of different groups of a society is “valued” by the rest of the society. In our approach, a “convenient” agreement is a core partition, so this paper is devoted to relate the core of a hedonic game with the core of a hedonic game played by the sets of representatives. Thus we have to tackle the existence problem of core partitions in a reduced game where the only coalitions that matter are those prescribed by the distribution as a set of representatives. We also study how a distribution determines the whole set of core partitions of a hedonic game. As an interesting example, we introduce the notion of hedonic partitioning game, which resembles partitioning games studied in the case where a utility, transferable or not, is present. The existence result obtained in this new class of games is later used to provide a nonconstructive proof of the existence of a stable matching in the marriage model.

scholarly journals A Coalition Formation Game Approach for Efficient Cooperative Multi-UAV Deployment

2018 ◽  
Vol 8 (12) ◽  
pp. 2427 ◽  
Author(s):  
Lang Ruan ◽  
Jin Chen ◽  
Qiuju Guo ◽  
Han Jiang ◽  
Yuli Zhang ◽  
...  
Keyword(s):  
Coalition Formation ◽  
Cooperative Control ◽  
Base Station ◽  
Transmission Mechanism ◽  
Coalition Formation Game ◽  
Stable Partition ◽  
Aerial Vehicle ◽  
Considerable Benefit ◽  
Formation Game ◽  
Multi Uav

Unmanned aerial vehicle (UAV) cooperative control has been an important issue in UAV-assisted sensor networks, thanks to the considerable benefit obtained from the cooperative mechanism of UAVs being applied as a flying base station. In a coverage scenarios, the trade-off between coverage and transmission performance often makes deployment of UAVs fall into a dilemma, since both indexes are related to the distance between UAVs. To address this issue, UAV coverage and data transmission mechanism is analyzed in this paper; then, an efficient multi-UAV cooperative deployment model is proposed. The problem is modeled as a coalition formation game (CFG). The CFG with Pareto order is proved to have a stable partition. Then, an effective approach consisting of coverage deployment and coalition selection is designed, wherein UAVs can decide strategies cooperatively to achieve better coverage performance. Combining analysis of game approach, coalition selection and the position deployment algorithm based on Pareto order (CSPDA-PO) is designed to execute coverage deployment and coalition selection. Finally, simulation results are shown to validate the proposed approach based on an efficient multi-UAV cooperative deployment model.

scholarly journals Strategyproof Mechanisms for Additively Separable and Fractional Hedonic Games

2021 ◽  
Vol 70 ◽  
Author(s):  
Michele Flammini ◽  
Bojana Kodric ◽  
Gianpiero Monaco ◽  
Qiang Zhang
Keyword(s):  
Computational Complexity ◽  
Coalition Formation ◽  
Upper Bounds ◽  
Additive Functions ◽  
Lower And Upper Bounds ◽  
Welfare Maximization ◽  
Social Welfare Maximization ◽  
Hedonic Games ◽  
Selfish Agents ◽  
True Preferences

Additively separable hedonic games and fractional hedonic games have received considerable attention in the literature. They are coalition formation games among selfish agents based on their mutual preferences. Most of the work in the literature characterizes the existence and structure of stable outcomes (i.e., partitions into coalitions) assuming that preferences are given. However, there is little discussion of this assumption. In fact, agents receive different utilities if they belong to different coalitions, and thus it is natural for them to declare their preferences strategically in order to maximize their benefit. In this paper we consider strategyproof mechanisms for additively separable hedonic games and fractional hedonic games, that is, partitioning methods without payments such that utility maximizing agents have no incentive to lie about their true preferences. We focus on social welfare maximization and provide several lower and upper bounds on the performance achievable by strategyproof mechanisms for general and specific additive functions. In most of the cases we provide tight or asymptotically tight results. All our mechanisms are simple and can be run in polynomial time. Moreover, all the lower bounds are unconditional, that is, they do not rely on any computational complexity assumptions.

scholarly journals Relaxed Core Stability in Fractional Hedonic Games

2021 ◽  
Author(s):  
Angelo Fanelli ◽  
Gianpiero Monaco ◽  
Luca Moscardelli
Keyword(s):  
Coalition Formation ◽  
Core Stability ◽  
Multi Agent Systems ◽  
Agent Systems ◽  
The Core ◽  
Utility Gain ◽  
Tiny Amount ◽  
Multi Agent ◽  
Hedonic Games ◽  
Stable Solutions

The core is a well-known and fundamental notion of stability in games intended to model coalition formation such as hedonic games. The fact that the number of deviating agents (that have to coordinate themselves) can be arbitrarily high, and the fact that agents may benefit only by a tiny amount from their deviation (while they could incur in a cost for deviating), suggest that the core is not able to suitably model many practical scenarios in large and highly distributed multi-agent systems. For this reason, we consider relaxed core stable outcomes where the notion of permissible deviations is modified along two orthogonal directions: the former takes into account the size of the deviating coalition, and the latter the amount of utility gain for each member of the deviating coalition. These changes result in two different notions of stability, namely, the q-size core and k-improvement core. We investigate these concepts of stability in fractional hedonic games, that is a well-known subclass of hedonic games for which core stable outcomes are not guaranteed to exist and it is computationally hard to decide nonemptiness of the core. Interestingly, the considered relaxed notions of core also possess the appealing property of recovering, in some notable cases, the convergence, the existence and the possibility of computing stable solutions in polynomial time.

scholarly journals Loyalty in Cardinal Hedonic Games

2021 ◽  
Author(s):  
Martin Bullinger ◽  
Stefan Kober
Keyword(s):  
Coalition Formation ◽  
Pareto Optimal ◽  
Common Theme ◽  
Multi Agent Systems ◽  
Agent Systems ◽  
The Core ◽  
Coalition Structures ◽  
Group Stability ◽  
Multi Agent ◽  
Hedonic Games

A common theme of decision making in multi-agent systems is to assign utilities to alternatives, which individuals seek to maximize. This rationale is questionable in coalition formation where agents are affected by other members of their coalition. Based on the assumption that agents are benevolent towards other agents they like to form coalitions with, we propose loyalty in hedonic games, a binary relation dependent on agents' utilities. Given a hedonic game, we define a loyal variant where agents' utilities are defined by taking the minimum of their utility and the utilities of agents towards which they are loyal. This process can be iterated to obtain various degrees of loyalty, terminating in a locally egalitarian variant of the original game. We investigate axioms of group stability and efficiency for different degrees of loyalty. Specifically, we consider the problem of finding coalition structures in the core and of computing best coalitions, obtaining both positive and intractability results. In particular, the limit game possesses Pareto optimal coalition structures in the core.

Dismantling White Privilege: The Black Lives Matter Movement and Environmental Justice in Canada

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Cheryl Teelucksingh
Keyword(s):  
United States ◽  
Critical Race Theory ◽  
Environmental Justice ◽  
White Supremacy ◽  
Jim Crow ◽  
The United States ◽  
Conceptual Tool ◽  
Public Monuments ◽  
Black Lives Matter ◽  
Jim Crow Era

On August 12, 2017, in Charlottesville, Virginia, alt-right/White supremacy groups and Black Lives Matter (BLM) supporters came face-to-face regarding what to do about public monuments that celebrate key figures from slavery and the Jim Crow era. White supremacists and White nationalists did not hide their racist ideologies as they demanded that their privileged place in history not be erased. The BLM movement, which challenges state-sanctioned anti-Black racism, was ready to confront themes of White discontent and reverse racism, critiques of political correctness, and the assumption that racialized people should know their place and be content to be the subordinate other.It is easy to frame the events in Charlottesville as indicative of US-specific race problems. However, a sense that White spaces should prevail and an ongoing history of anti-Black racism are not unique to the United States. The rise of Canadian activism under the BLM banner also signals a movement to change Canadian forms of institutional racism in policing, education, and the labor market. This article responds to perceptions that the BLM movement has given insufficient attention to environmental concerns (Pellow 2016; Halpern 2017). Drawing on critical race theory as a conceptual tool, this article focuses on the Canadian context as part of the author’s argument in favor of greater collaboration between BLM and the environmental justice (EJ) movement in Canada. This article also engages with the common stereotype that Blacks in Canada have it better than Blacks in the United States.

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