Asynchronous backtracking without adding links: a new member in the ABT family

Bessière, Christian; Maestre, Arnold; Brito, Ismel; Meseguer, Pedro

doi:10.1016/j.artint.2004.10.002

Cited by 71 publications

(130 citation statements)

References 10 publications

Supporting

Mentioning

130

Contrasting

Order By: Relevance

“…There are several forms of how new nogoods are generated. In [2], when an agent has no consistent values, it resolves its nogoods following a procedure described in [1]. In this paper we consider this last version.…”

Section: Asynchronous Backtrackingmentioning

confidence: 99%

“…An ABT agent makes its own decisions, informs other agents about them, and no agent has to wait for the others' decisions. The algorithm computes a global consistent solution (or detects that no solution exists) in finite time; its correctness and completeness have been proved [13,2]. ABT requires constraints to be directed.…”

Section: Asynchronous Backtrackingmentioning

confidence: 99%

“…To achieve this, agents assign their variables and exchange messages on these assignments, which allows them to check their consistency with respect to problem constraints. Several synchronous and asynchronous solving algorithms have been proposed [12,13,8,2,5]. While synchronous algorithms are easier to understand and implement, asynchronous ones are more robust.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Connecting ABT with Arc Consistency

Brito

Meseguer

2008

Lecture Notes in Computer Science

Self Cite

View full text Add to dashboard Cite

Abstract. ABT is the reference algorithm for asynchronous distributed constraint satisfaction. When searching, ABT produces nogoods as justifications of deleted values. When one of such nogoods has an empty left-hand side, the considered value is eliminated unconditionally, once and for all. This value deletion can be propagated using standard arc consistency techniques, producing new deletions in the domains of other variables. This causes substantial reductions in the search effort required to solve a class of problems. We also extend this idea to the propagation of conditional deletions, something already proposed in the past. We provide experimental results that show the benefits of the proposed approach, especially considering communication cost.

show abstract

Section: Asynchronous Backtrackingmentioning

confidence: 99%

Section: Asynchronous Backtrackingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Connecting ABT with Arc Consistency

Brito

Meseguer

2008

Lecture Notes in Computer Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…Asynchronous Backtracking was first presented by Yokoo [25,26] and was developed further and studied in [2,3,10,20]. Agents in the ABT algorithm perform assignments asynchronously according to their current view of the system's state.…”

Section: Introductionmentioning

confidence: 99%

“…[23,25]). To achieve this goal, agents check the value assignments to their variables for local consistency and exchange messages with other agents, to check consistency of their proposed assignments against constraints with variables owned by different agents [2].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Ordering for Asynchronous Backtracking on DisCSPs

Zivan

Meisels

2005

Principles and Practice of Constraint Programming - CP 2005

View full text Add to dashboard Cite

An algorithm that performs asynchronous backtracking on distributed CSPs, with dynamic ordering of agents is proposed, ABT DO. Agents propose reorderings of lower priority agents and send these proposals whenever they send assignment messages. Changes of ordering triggers a different computation of N ogoods. The dynamic ordered asynchronous backtracking algorithm uses polynomial space, similarly to standard ABT. The ABT DO algorithm with three different ordering heuristics is compared to standard ABT on randomly generated DisCSPs. A Nogoodtriggered heuristic, inspired by dynamic backtracking, is found to outperform static order ABT by a large factor in run-time and improve the network load.

show abstract

Algorithms and Ordering Heuristics for Distributed Constraint Satisfaction Problems

Wahbi¹

2013

View full text Add to dashboard Cite

Distributed Constraint Satisfaction Problems (DisCSP) is a general framework for solving distributed problems. DisCSP have a wide range of applications in multi-agent coordination. In this thesis, we extend the state of the art in solving the DisCSPs by proposing several algorithms. Firstly, we propose the Nogood-Based Asynchronous Forward Checking (AFC-ng), an algorithm based on Asynchronous Forward Checking (AFC). However, instead of using the shortest inconsistent partial assignments, AFC-ng uses nogoods as justifications of value removals. Unlike AFC, AFC-ng allows concurrent backtracks to be performed at the same time coming from different agents having an empty domain to different destinations. Then, we propose the Asynchronous Forward-Checking Tree (AFCtree). In AFC-tree, agents are prioritized according to a pseudo-tree arrangement of the constraint graph. Using this priority ordering, AFC-tree performs multiple AFC-ng processes on the paths from the root to the leaves of the pseudo-tree. Next, we propose to maintain arc consistency asynchronously on the future agents instead of only maintaining forward checking. Two new synchronous search algorithms that maintain arc consistency asynchronously (MACA) are presented. After that, we developed the Agile Asynchronous Backtracking (Agile-ABT), an asynchronous dynamic ordering algorithm that does not follow the standard restrictions in asynchronous backtracking algorithms. The order of agents appearing before the agent receiving a backtrack message can be changed with a great freedom while ensuring polynomial space complexity. Next, we present a corrigendum of the protocol designed for establishing the priority between orders in the asynchronous backtracking algorithm with dynamic ordering using retroactive heuristics (ABT_DO-Retro). Finally, the new version of the DisChoco open-source platform for solving distributed constraint reasoning problems is described. The new version is a complete redesign of the DisChoco platform. DisChoco 2.0 is an open source Java library which aims at implementing distributed constraint reasoning algorithms.

show abstract

Asynchronous backtracking without adding links: a new member in the ABT family

Cited by 71 publications

References 10 publications

Connecting ABT with Arc Consistency

Connecting ABT with Arc Consistency

Dynamic Ordering for Asynchronous Backtracking on DisCSPs

Algorithms and Ordering Heuristics for Distributed Constraint Satisfaction Problems

Contact Info

Product

Resources

About