A theoretical evaluation of selected backtracking algorithms

Kondrak, Grzegorz; Beek, Peter van der

doi:10.1016/s0004-3702(96)00027-6

Cited by 107 publications

(72 citation statements)

References 12 publications

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“…Completeness follows from this fact in analogy to the completeness proof for centralized backtracking in [7]. By Lemma 3, it is enough to prove completeness for the case where there are no Not_OK messages.…”

Section: Lemma 3 Consistent C Pas That Are Not Sent Forward For Extenmentioning

confidence: 86%

Asynchronous Forward-checking for DisCSPs

Meisels

Zivan

2007

Constraints

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A new search algorithm for solving distributed constraint satisfaction problems (DisCSPs) is presented. Agents assign variables sequentially, but perform forward checking asynchronously. The asynchronous forward-checking algorithm (AFC) is a distributed search algorithm that keeps one consistent partial assignment at all times. Forward checking is performed by sending copies of the partial assignment to all unassigned agents concurrently. The algorithm is described in detail and its correctness proven. The sequential assignment method of AFC leads naturally to dynamic ordering of agents during search. Several ordering heuristics are presented. The three best heuristics are evaluated and shown to improve the performance of AFC with static order by a large factor. An experimental comparison of AFC to asynchronous backtracking ( ABT) on randomly generated DisCSPs is also presented. AFC with ordering heuristics outperforms ABT by a large factor on the harder instances of random DisCSPs. These results hold for two measures of performance: number of non-concurrent constraints checks and number of messages sent.

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Section: Lemma 3 Consistent C Pas That Are Not Sent Forward For Extenmentioning

confidence: 86%

Asynchronous Forward-checking for DisCSPs

Meisels

Zivan

2007

Constraints

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“…Several researchers have tried to combine lookahead strategies with some learning techniques. While CBJ [9] brings some improvements to FC, it seems to alter MAC [2]. The explanation can be that CBJ brings pruning at an average cost superior to the average efficiency of MAC.…”

Section: Discussionmentioning

confidence: 97%

“…Typical intelligent backtrackers are the Constraint-Based Back-jumping (CBJ), the BackMarking [9], the Dynamic Backtracking [6] and the Partial Order Dynamic Backtracking [3]. The most popular lookahead strategies are Forward Checking (FC) and Maintaining Arc-Consistency (MAC) [11].…”

Section: Introductionmentioning

confidence: 99%

Ways of Maintaining Arc Consistency in Search Using the Cartesian Representation

Silaghi

Sam-Haroud

Faltings

2000

New Trends in Constraints

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Abstract. The search space of constraint satisfaction problems (CSPs) can be reduced by using value interchangeability. This notion consists of aggregating subsets of values that behave similarly on the future branches of the search. , is a typical backtracking algorithm using value interchangeability. It uses the Cartesian product representation of the search space (CPR) which aggregates partial solutions and proves particularly useful for finding and representing all solutions of a CSP. It is assessed that maintaining arc-consistency (MAC) is the most efficient general algorithm for solving hard problems. A few work on combining MAC with CPR exists. In this paper we study comparatively two other possible alternatives of MAC-CPR.

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“…The joint optimization of scheduling and register allocation is addressed by [19] and [20]. General backtracking algorithms for constraint satisfaction problems have been evaluated [21].…”

Section: Related Workmentioning

confidence: 99%

Efficient backtracking instruction schedulers

Abraham

Meleis

Baev

Proceedings 2000 International Conference on Parallel Architectures and Compilation Techniques (Cat. No.PR00622)

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Current schedulers for acyclic regions schedule operations in dependence order and never revisit or undo a scheduling decision on any operation. In contrast, backtracking schedulers may unschedule already scheduled operations, in order to make space for the operation currently being scheduled. Backtracking schedulers have the potential for generating better schedules, e.g. more effectively filling branch delay slots, but are more compile-time intensive and therefore, not considered practical for production use.In this report, we first describe conventional cycle and list schedulers followed by two novel backtracking schedulers. The full-backtracking OperBT scheduler enables backtracking for all operations and unschedules already scheduled operations to make space for the current operation, if, among other situations, there is no available slot that satisfies dependence constraints. This scheduler is effective in generating high quality schedules that for instance, successfully fill branch delay slots but likely backtracks too often. The selective backtracking ListBT scheduler enables backtracking only when scheduling certain types of operations, for which backtracking is likely to be advantageous, e.g. branches. When not scheduling these operations (or operations that were displaced through backtracking), the scheduler reverts to efficient scheduling in dependence order. The ListBT scheduler backtracks less often than the OperBT scheduler. Both schedulers successfully fill a large fraction of the branch delay slots and improve performance of the scheduled code significantly.

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A theoretical evaluation of selected backtracking algorithms

Cited by 107 publications

References 12 publications

Asynchronous Forward-checking for DisCSPs

Asynchronous Forward-checking for DisCSPs

Ways of Maintaining Arc Consistency in Search Using the Cartesian Representation

Efficient backtracking instruction schedulers

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