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Putting the “smarts” into the smart grid: a grand challenge for artificial intelligence
 Communications of the ACM
"... The phenomenal growth in material wealth experienced in developed countries throughout the twentieth century has largely been driven by the availability of cheap energy derived from fossil fuels (originally coal, then oil, and most ..."
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Cited by 46 (7 self)
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The phenomenal growth in material wealth experienced in developed countries throughout the twentieth century has largely been driven by the availability of cheap energy derived from fossil fuels (originally coal, then oil, and most
Cooperative Games with Overlapping Coalitions
"... In the usual models of cooperative game theory, the outcome of a coalition formation process is either the grand coalition or a coalition structure that consists of disjoint coalitions. However, in many domains where coalitions are associated with tasks, an agent may be involved in executing more th ..."
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Cited by 23 (9 self)
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In the usual models of cooperative game theory, the outcome of a coalition formation process is either the grand coalition or a coalition structure that consists of disjoint coalitions. However, in many domains where coalitions are associated with tasks, an agent may be involved in executing more than one task, and thus may distribute his resources among several coalitions. To tackle such scenarios, we introduce a model for cooperative games with overlapping coalitions—or overlapping coalition formation (OCF) games. We then explore the issue of stability in this setting. In particular, we introduce a notion of the core, which generalizes the corresponding notion in the traditional (nonoverlapping) scenario. Then, under some quite general conditions, we characterize the elements of the core, and show that any element of the core maximizes the social welfare. We also introduce a concept of balancedness for overlapping coalitional games, and use it to characterize coalition structures that can be extended to elements of the core. Finally, we generalize the notion of convexity to our setting, and show that under some natural assumptions convex games have a nonempty core. Moreover, we introduce two alternative notions of stability in OCF that allow a wider range of deviations, and explore the relationships among the corresponding definitions of the core, as well as the classic (nonoverlapping) core and the Aubin core. We illustrate the general properties of the three cores, and also study them from a computational perspective, thus obtaining additional insights into their fundamental structure. 1.
Coalition Structure Generation in MultiAgent Systems With Positive and Negative Externalities
"... Coalition structure generation has received considerable attention in recent research. Several algorithms have been proposed to solve this problem in Characteristic Function Games (CFGs), where every coalition is assumed to perform equally well in any coalition structure containing it. In contrast, ..."
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Cited by 21 (7 self)
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Coalition structure generation has received considerable attention in recent research. Several algorithms have been proposed to solve this problem in Characteristic Function Games (CFGs), where every coalition is assumed to perform equally well in any coalition structure containing it. In contrast, very little attention has been given to the more general Partition Function Games (PFGs), where a coalition’s effectiveness may change from one coalition structure to another. In this paper, we deal with PFGs with positive and negative externalities. In this context, we identify the minimum search that is required in order to establish a bound on the quality of the best coalition structure found. We then develop an anytime algorithm that improves this bound with further search, and show that it outperforms the existing stateoftheart algorithms by orders of magnitude. 1
A Distributed Algorithm for Anytime Coalition Structure Generation
"... A major research challenge in multiagent systems is the problem of partitioning a set of agents into mutually disjoint coalitions, such that the overall performance of the system is optimized. This problem is difficult because the search space is very large: the number of possible coalition structu ..."
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Cited by 19 (9 self)
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A major research challenge in multiagent systems is the problem of partitioning a set of agents into mutually disjoint coalitions, such that the overall performance of the system is optimized. This problem is difficult because the search space is very large: the number of possible coalition structures increases exponentially with the number of agents. Although several algorithms have been proposed to tackle this Coalition Structure Generation (CSG) problem, all of them suffer from being inherently centralized, which leads to the existence of a performance bottleneck and a single point of failure. In this paper, we develop the first decentralized algorithm for solving the CSG problem optimally. In our algorithm, the necessary calculations are distributed among the agents, instead of being carried out centrally by a single agent (as is the case in all the available algorithms in the literature). In this way, the search can be carried out in a much faster and more robust way, and the agents can share the burden of the calculations. The algorithm combines, and improves upon, techniques from two existing algorithms in the literature, namely DCVC [5] and IP [9], and applies novel techniques for filtering the input and reducing the interagent communication load.
Decentralised Coordination in RoboCup Rescue
, 2009
"... Emergency responders are faced with a number of significant challenges when managing major disasters. First, the number of rescue tasks posed is usually larger than the number of responders (or agents) and the resources available to them. Second, each task is likely to require a different level of e ..."
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Cited by 14 (4 self)
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Emergency responders are faced with a number of significant challenges when managing major disasters. First, the number of rescue tasks posed is usually larger than the number of responders (or agents) and the resources available to them. Second, each task is likely to require a different level of effort in order to be completed by its deadline. Third, new tasks may continually appear or disappear from the environment, thus requiring the responders to quickly recompute their allocation of resources. Fourth, forming teams or coalitions of multiple agents from different agencies is vital since no single agency will have all the resources needed to save victims, unblock roads, and extinguish the fires which might erupt in the disaster space. Given this, coalitions have to be efficiently selected and scheduled to work across the disaster space so as to maximise the number of lives and the portion of the infrastructure saved. In particular, it is important that the selection of such coalitions should be performed in a decentralised fashion in order to avoid a single point of failure in the system. Moreover, it is critical that responders communicate only locally given they are likely
Constrained Coalition Formation
"... The conventional model of coalition formation considers every possible subset of agents as a potential coalition. However, in many realworld applications, there are inherent constraints on feasible coalitions: for instance, certain agents may be prohibited from being in the same coalition, or the c ..."
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Cited by 13 (6 self)
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The conventional model of coalition formation considers every possible subset of agents as a potential coalition. However, in many realworld applications, there are inherent constraints on feasible coalitions: for instance, certain agents may be prohibited from being in the same coalition, or the coalition structure may be required to consist of coalitions of the same size. In this paper, we present the first systematic study of constrained coalition formation (CCF). We propose a general framework for this problem, and identify an important class of CCF settings, where the constraints specify which groups of agents should/should not work together. We describe a procedure that transforms such constraints into a structured input that allows coalition formation algorithms to identify, without any redundant computations, all the feasible coalitions. We then use this procedure to develop an algorithm for generating an optimal (welfaremaximizing) constrained coalition structure, and show that it outperforms existing stateoftheart approaches by several orders of magnitude.
On Representing Coalitional Games with Externalities
"... We consider the issue of representing coalitional games in multiagent systems with externalities (i.e., in systems where the performance of one coalition may be affected by other coexisting coalitions). In addition to the conventional partition function game representation (P F G), we propose a num ..."
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Cited by 12 (6 self)
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We consider the issue of representing coalitional games in multiagent systems with externalities (i.e., in systems where the performance of one coalition may be affected by other coexisting coalitions). In addition to the conventional partition function game representation (P F G), we propose a number of new representations based on a new notion of externalities. In contrast to conventional game theory, our new concept is not related to the process by which the coalitions are formed, but rather to the effect that each coalition may have on the entire system and vice versa. We show that the new representations are fully expressive and, for many classes of games, more concise than the conventional P F G. Building upon these new representations, we propose a number of approaches to solve the coalition structure generation problem in systems with externalities. We show that, if externalities are characterised by various degrees of regularity, the new representations allow us to adapt coalition structure generation algorithms that were originally designed for domains with no externalities, so that they can be used when externalities are present. Finally, building upon [16] and [9], we present a unified method to solve the coalition structure generation problem in any system, with or without externalities, provided sufficient information is available.
A hybrid algorithm for coalition structure generation
 In Twenty Sixth Conference on Artificial Intelligence (AAAI12
, 2012
"... The current stateoftheart algorithm for optimal coalition structure generation is IDPIP—an algorithm that combines IDP (a dynamic programming algorithm due to Rahwan and Jennings, 2008b) with IP (a treesearch algorithm due to Rahwan et al., 2009). In this paper we analyse IDPIP, highlight its ..."
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Cited by 11 (7 self)
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The current stateoftheart algorithm for optimal coalition structure generation is IDPIP—an algorithm that combines IDP (a dynamic programming algorithm due to Rahwan and Jennings, 2008b) with IP (a treesearch algorithm due to Rahwan et al., 2009). In this paper we analyse IDPIP, highlight its limitations, and then develop a new approach for combining IDP with IP that overcomes these limitations. 1
Computing Desirable Partitions in Additively Separable Hedonic Games
, 2011
"... An important aspect in systems of multiple autonomous agents is the exploitation of synergies via coalition formation. Additively separable hedonic games are a fundamental class of coalition formation games in which each player has a value for any other player and the value of a coalition to a parti ..."
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Cited by 11 (4 self)
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An important aspect in systems of multiple autonomous agents is the exploitation of synergies via coalition formation. Additively separable hedonic games are a fundamental class of coalition formation games in which each player has a value for any other player and the value of a coalition to a particular player is simply the sum of the values he assigns to the members of his coalition. In this paper, we consider a number of solution concepts from cooperative game theory, welfare theory, and social choice theory as criteria for desirable partitions in hedonic games. We then conduct a detailed computational analysis of computing, checking the existence of, and verifying stable, fair, optimal, and popular partitions for additively separable hedonic games.
Minimum search to establish worstcase guarantees in coalition structure generation
 In IJCAI’11: Twenty Second International Joint Conference on Artificial Intelligence
, 2011
"... Coalition formation is a fundamental research topic in multiagent systems. In this context, while it is desirable to generate a coalition structure that maximizes the sum of the values of the coalitions, the space of possible solutions is often too large to allow exhaustive search. Thus, a fundamen ..."
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Cited by 10 (7 self)
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Coalition formation is a fundamental research topic in multiagent systems. In this context, while it is desirable to generate a coalition structure that maximizes the sum of the values of the coalitions, the space of possible solutions is often too large to allow exhaustive search. Thus, a fundamental open question in this area is the following: Can we search through only a subset of coalition structures, and be guaranteed to find a solution that is within a desirable bound β from optimum? If so, what is the minimum such subset? To date, the above question has only been partially answered by Sandholm et al. in their seminal work on anytime coalition structure generation [Sandholm et al., 1999]. More specifically, they identified minimum subsets to be searched for two particular bounds: β = n and β = dn/2e. Nevertheless, the question remained open for other values of β. In this paper, we provide the complete answer to this question. 1