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A Decentralized Variable Ordering Method for Distributed Constraint Optimization
 IN PROCEEDINGS OF THE FORTH INTERNATIONAL JOINT CONFERENCE ON AUTONOMOUS AGENTS AND MULTIAGENT SYSTEMS
, 2005
"... Many different multiagent problems, such as distributed scheduling can be formalized as distributed constraint optimization. Ordering the constraint variables is an important preprocessing step of the ADOPT algorithm [1], the state of the art method of solving distributed constraint optimization pr ..."
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Cited by 13 (1 self)
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Many different multiagent problems, such as distributed scheduling can be formalized as distributed constraint optimization. Ordering the constraint variables is an important preprocessing step of the ADOPT algorithm [1], the state of the art method of solving distributed constraint optimization problems (DCOP). Currently ADOPT uses depthfirst search (DFS) trees for that purpose. For certain classes of tasks DFS ordering does not exploit the problem structure as compared to pseudotree ordering [2]. Also the variables are currently ordered in a centralized manner, which requires global information about the problem structure. We present a variable ordering algorithm, which is both decentralized and makes use of pseudotrees, thus exploiting the problem structure when possible. This allows to apply ADOPT to domains, where global information is unavailable, and find solutions more efficiently. The worstcase pseudotree depth resulting from our algorithm is # 2kn, where n is the number of variables, and k is maximum block size in constraint graph. The algorithm has space complexity of O(kn) and time complexity of O(n+ ), where E is the set of edges in a constraint graph.
Dynamic Configuration of Agent Organizations
"... It is useful to impose organizational structure over multiagent coalitions. Hierarchies, for instance, allow for compartmentalization of tasks: if organized correctly, tasks in disjoint subtrees of the hierarchy may be performed in parallel. Given a notion of the way in which a group of agents need ..."
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Cited by 11 (0 self)
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It is useful to impose organizational structure over multiagent coalitions. Hierarchies, for instance, allow for compartmentalization of tasks: if organized correctly, tasks in disjoint subtrees of the hierarchy may be performed in parallel. Given a notion of the way in which a group of agents need to interact, the Dynamic Distributed Multiagent Hierarchy Generation (DynDisMHG) problem is to determine the best hierarchy that might expedite the process of coordination. This paper introduces a distributed algorithm, called Mobed, for both constructing and maintaining organizational agent hierarchies, enabling exploitation of parallelism in distributed problem solving. The algorithm is proved correct and it is shown that individual additions of agents to the hierarchy will run in an amortized linear number of rounds. The hierarchies resulting after perturbations to the agent coalition have constantbounded edit distance, making Mobed very well suited to highly dynamic problems. 1
Synchronous, asynchronous and hybrid algorithms for DisCSP
 IN: WORKSHOP ON DCR04, CP2004
, 2004
"... There is some debate about the kind of algorithms that are most suitable to solve DisCSP. Synchronous algorithms exchange updated information with a low degree of parallelism. Asynchronous algorithms use less updated information with a higher parallelism. Hybrid algorithms combine both features. Lat ..."
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Cited by 11 (1 self)
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There is some debate about the kind of algorithms that are most suitable to solve DisCSP. Synchronous algorithms exchange updated information with a low degree of parallelism. Asynchronous algorithms use less updated information with a higher parallelism. Hybrid algorithms combine both features. Lately, there is some evidence that synchronous algorithms could be more efficient than asynchronous ones for one problem class. In this paper, we present some improvements on existing synchronous and asynchronous algorithms, as well as a new hybrid algorithm. We provide an empirical investigation of these algorithms onqueens and binary random DisCSPs.
On communication in solving distributed constraint satisfaction problems
 In MultiAgent Systems and Applications IV, Proc. 4th International Central and Eastern European Conference on MultiAgent Systems, CEEMAS 2005
, 2005
"... Abstract. Distributed Constraint Satisfaction Problems (DCSP) is a general framework for multiagent coordination and conflict resolution. In most DCSP algorithms, interagent communication is restricted to only exchanging values of variables, since any additional informationexchange is assumed to ..."
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Abstract. Distributed Constraint Satisfaction Problems (DCSP) is a general framework for multiagent coordination and conflict resolution. In most DCSP algorithms, interagent communication is restricted to only exchanging values of variables, since any additional informationexchange is assumed to lead to significant communication overheads and to a breach of privacy. This paper provides a detailed experimental investigation of the impact of interagent exchange of additional legal values among agents, within a collaborative setting. We provide a new runtime model that takes into account the overhead of the additional communication in various computing and networking environments. Our investigation of more than 300 problem settings with the new runtime model (i) shows that DCSP strategies with additional informationexchange can lead to big speedups in a significant range of settings; and (ii) provides categorization of problem settings with big speedups by the DCSP strategies based on extra communication, enabling us to selectively apply the strategies to a given domain. This paper not only provides a useful method for performance measurement to the DCSP community, but also shows the utility of additional communication in DCSP. 1
Reducing Redundant Messages in the Asychronous Backtracking Algorithm
 SIXTH INTERNATIONAL WORKSHOP ON DISTRIBUTED CONSTRAINT REASONING
, 2005
"... We show how the Asynchronous Backtracking Algorithm, a well known distributed constraint satisfaction algorithm, produces unnecessary messages. Our new optimized algorithm reduces the number of messages by implementing message management mechanism. Test show ..."
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We show how the Asynchronous Backtracking Algorithm, a well known distributed constraint satisfaction algorithm, produces unnecessary messages. Our new optimized algorithm reduces the number of messages by implementing message management mechanism. Test show
分布式约束满足问题研究及其进展∗
"... Artificial Intelligence, for example scheduling, planning, resource allocation etc., are formally distributed now, which turn into a kind of multiagent system problems. Accordingly, the standard constraint satisfaction problems turn into distributed constraint satisfaction problems, which become th ..."
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Artificial Intelligence, for example scheduling, planning, resource allocation etc., are formally distributed now, which turn into a kind of multiagent system problems. Accordingly, the standard constraint satisfaction problems turn into distributed constraint satisfaction problems, which become the general architecture for resolving multiagent system. This paper first briefly introduces the basic concepts of distributed CSPs, and then summarizes the basic and the improved algorithms. Their efficiency and performance are analyzed and the typical applications of distributed CSPs in recent years are discussed. Finally, this paper presents the extensions of the basic formalization and the research trends in this area. Recent related work indicates that the future work will focus on