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18
Algorithms for Distributed Constraint Satisfaction: A Review
 In CP
, 2000
"... . When multiple agents are in a shared environment, there usually exist constraints among the possible actions of these agents. A distributed constraint satisfaction problem (distributed CSP) is a problem to find a consistent combination of actions that satisfies these interagent constraints. Vario ..."
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Cited by 248 (11 self)
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. When multiple agents are in a shared environment, there usually exist constraints among the possible actions of these agents. A distributed constraint satisfaction problem (distributed CSP) is a problem to find a consistent combination of actions that satisfies these interagent constraints. Various application problems in multiagent systems can be formalized as distributed CSPs. This paper gives an overview of the existing research on distributed CSPs. First, we briefly describe the problem formalization and algorithms of normal, centralized CSPs. Then, we show the problem formalization and several MAS application problems of distributed CSPs. Furthermore, we describe a series of algorithms for solving distributed CSPs, i.e., the asynchronous backtracking, the asynchronous weakcommitment search, the distributed breakout, and distributed consistency algorithms. Finally,we showtwo extensions of the basic problem formalization of distributed CSPs, i.e., handling multiple local variables, and dealing with overconstrained problems. Keywords: Constraint Satisfaction, Search, distributed AI 1.
Distributed partial constraint satisfaction problem
 Principles and Practice of Constraint Programming
, 1997
"... Abstract. Many problems in multiagent systems can be described as distributed Constraint Satisfaction Problems (distributed CSPs), where the goal is to nd a set of assignments to variables that satis es all constraints among agents. However, when real problems are formalized as distributed CSPs, th ..."
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Cited by 71 (14 self)
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Abstract. Many problems in multiagent systems can be described as distributed Constraint Satisfaction Problems (distributed CSPs), where the goal is to nd a set of assignments to variables that satis es all constraints among agents. However, when real problems are formalized as distributed CSPs, they are often overconstrained and have no solution that satis es all constraints. This paper provides the Distributed Partial Constraint Satisfaction Problem (DPCSP) as a new framework for dealing with overconstrained situations. We also present new algorithms for solving Distributed Maximal Constraint Satisfaction Problems (DMCSPs), which belong to an important class of DPCSP. The algorithms are called the Synchronous Branch and Bound (SBB) and the Iterative Distributed Breakout (IDB). Both algorithms were tested on hard classes of overconstrained random binary distributed CSPs. The results can be summarized as SBB is preferable when we are mainly concerned with the optimality ofasolution, while IDB is preferable when we want to get a nearly optimal solution quickly. 1
Analysis of Distributed ArcConsistency Algorithms
, 1997
"... Consistency techniques can significantly reduce the search space of constraint satisfaction problems (CSP). In particular, arcconsistency algorithms, such as AC3 [7], AC4 [8] and AC6 [2], have been designed. In [9], we presented DisAC4, a coarsegrained parallel algorithm designed for distribut ..."
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Cited by 51 (0 self)
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Consistency techniques can significantly reduce the search space of constraint satisfaction problems (CSP). In particular, arcconsistency algorithms, such as AC3 [7], AC4 [8] and AC6 [2], have been designed. In [9], we presented DisAC4, a coarsegrained parallel algorithm designed for distributed memory computer using message passing, which is a distributed version of AC4. We extend here this result. We design DisAC3 and DisAC6. The communication scheme is also extended to allow communication during the propagation step of the consistency algorithms. All these algorithms were systematically experimented. An analysis of the different experiments shows that, as in the sequential case, DisAC6 provides the best performance and that DisAC3 outperforms DisAC4 on most tests. All the distributed algorithms shows a linear speedup. This lead to the conclusion that DisAC6 is a good candidate for distributed arcconsistency.
An Approach to Overconstrained Distributed Constraint Satisfaction Problems: Distributed Hierarchical Constraint Satisfaction
 PROCEEDINGS OF THE FOURTH INTERNATIONAL CONFERENCE ON MULTIAGENT SYSTEMS (ICMAS2000), PP.135–142
, 2000
"... Many problems in multiagent systems can be described as distributed CSPs. However, some reallife problem can be overconstrained and without a set of consistent variable values when described as a distributed CSP. We have presented the distributed partial CSP for handling such an overconstrained ..."
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Cited by 26 (6 self)
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Many problems in multiagent systems can be described as distributed CSPs. However, some reallife problem can be overconstrained and without a set of consistent variable values when described as a distributed CSP. We have presented the distributed partial CSP for handling such an overconstrained situation and the distributed maximal CSP as a subclass of distributed partial CSP. In this paper, we first show another subclass of distributed partial CSP, the distributed hierarchical CSP. Next, we present a series of new algorithms for solving a distributed hierarchical CSP, each of which is designed based on our previous distributed constraint satisfaction algorithms. Finally, we evaluate the performance of our new algorithms on distributed 3coloring problems in terms of optimality and anytime characteristics. The results show that our new algorithms perform much better than the previous algorithm for finding an optimal solution and produce good results for anytime characteristics.
An incomplete method for solving distributed valued constraint satisfaction problems
 In Proceedings of the AAAI Workshop on Constraints and Agents
, 1997
"... This paper sets a model for Distributed Valued Constraint Satisfaction Problems, and proposes an incompletemethod for solving such problems. This method is a greedy repair distributed algorithm which extends to the distributed case any greedy repair centralized algorithm. Experiments are carried out ..."
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Cited by 20 (0 self)
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This paper sets a model for Distributed Valued Constraint Satisfaction Problems, and proposes an incompletemethod for solving such problems. This method is a greedy repair distributed algorithm which extends to the distributed case any greedy repair centralized algorithm. Experiments are carried out on a realworld problem and show the practical interest of this method.
Strategies for distributed constraint satisfaction problems
 In Proc. of the 13th International Workshop on DAI
, 1994
"... Constraint satisfaction problems are important in AI. Various distributed and parallel computing strategies have been proposed to solve these problems. In this paper, these strategies are classified as distributedagentbased, parallelagentbased, and functionagentbased distributed problemsolvin ..."
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Cited by 13 (0 self)
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Constraint satisfaction problems are important in AI. Various distributed and parallel computing strategies have been proposed to solve these problems. In this paper, these strategies are classified as distributedagentbased, parallelagentbased, and functionagentbased distributed problemsolving strategies. These different strategies are presented and discussed. Parallelagentbased strategies are found to be very versatile. Computational experience is presented. 1
Generalized Dynamic Ordering for Asynchronous Backtracking On Discsps
"... Dynamic reordering of variables is known to be very important for solving constraint satisfaction problems (CSPs). Many attempts were made to apply this principle for improving ..."
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Cited by 9 (0 self)
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Dynamic reordering of variables is known to be very important for solving constraint satisfaction problems (CSPs). Many attempts were made to apply this principle for improving
ADOPTing: Unifying Asynchronous Distributed Optimization with Asynchronous Backtracking
, 2007
"... This article presents an asynchronous algorithm for solving Distributed Constraint Optimization problems (DCOPs). The proposed technique unifies asynchronous backtracking (ABT) and asynchronous distributed optimization (ADOPT) where valued nogoods enable more flexible reasoning and more opportunitie ..."
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Cited by 5 (2 self)
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This article presents an asynchronous algorithm for solving Distributed Constraint Optimization problems (DCOPs). The proposed technique unifies asynchronous backtracking (ABT) and asynchronous distributed optimization (ADOPT) where valued nogoods enable more flexible reasoning and more opportunities for communication, leading to an important speedup. While feedback can be sent in ADOPT by COST messages only to one predefined predecessor, our extension allows for sending such information to any relevant agent. The concept of valued nogood is an extension by Dago and Verfaille of the concept of classic nogood that associates the list of conflicting assignments with a cost and, optionally, with a set of references to culprit constraints. DCOPs have been shown to have very elegant distributed solutions, such as ADOPT, distributed asynchronous overlay (DisAO), or DPOP. These algorithms are typically tuned to minimize the longest causal chain of messages as a measure of how the algorithms will scale for systems with remote agents (with large latency in communication). ADOPT has the property of maintaining the initial distribution of the problem. To be efficient, ADOPT needs a preprocessing step consisting of computing a DepthFirst Search (DFS) tree on the constraint graph. Valued nogoods allow for automatically detecting and exploiting the best DFS tree compatible with the current ordering. To exploit such DFS trees it is now sufficient to ensure that they exist. Also, the inference rules available for valued nogoods help to exploit schemes of communication where more feedback is sent to higher priority agents. Together they result in an order of magnitude improvement.
Generalized English Auctions by relaxation in dynamic distributed CSPs with private constraints
 In Proc. of the IJCAI01 DCR Workshop
, 2001
"... Certain classes of negotiation problems lend themselves to strategies ensuring that no agent can gain by lying. Truth incentive protocols, among which Generalized Vickrey Auction (GVA) is one of the most famous, can then be used to centrally compute fair and efficient solutions. However, for problem ..."
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Cited by 3 (0 self)
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Certain classes of negotiation problems lend themselves to strategies ensuring that no agent can gain by lying. Truth incentive protocols, among which Generalized Vickrey Auction (GVA) is one of the most famous, can then be used to centrally compute fair and efficient solutions. However, for problems that allow no truth incentive protocols (e.g. problems with false name bids), English Auctions are prefered to GVA. In this paper we show how the framework of Distributed Constraint Satisfaction (DisCSP) with private constraints can be extended for modeling and solving negotiation problems such as English Auctions with multipleitems where bids can correspond to complex actions (selling, buying, or both). 1.
DFS ordering in Nogoodbased . . .
"... This work proposes an asynchronous algorithm for solving Distributed Constraint Optimization problems ..."
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This work proposes an asynchronous algorithm for solving Distributed Constraint Optimization problems