Optimal Scheduling of Contract Algorithms for Anytime Problem-Solving

Alejandro López-Ortiz Spyros Angelopoulos 1 Angele M Hamel
1 RO - Recherche Opérationnelle
LIP6 - Laboratoire d'Informatique de Paris 6
Abstract : A contract algorithm is an algorithm which is given, as part of the input, a specified amount of allowable computation time. The algorithm must then complete its execution within the allotted time. An interruptible algorithm, in contrast, can be interrupted at an arbitrary point in time, at which point it must report its currently best solution. It is known that contract algorithms can simulate interruptible algorithms using iterative deepening techniques. This simulation is done at a penalty in the performance of the solution, as measured by the so-called acceleration ratio. In this paper we give matching (i.e., optimal) upper and lower bounds for the acceleration ratio under such a simulation. We assume the most general setting in which n problem instances must be solved by means of scheduling executions of contract algorithms in $m$ identical parallel processors. This resolves an open conjecture of Bernstein, Filkenstein, and Zilberstein who gave an optimal schedule under the restricted setting of round robin and length-increasing schedules, but whose optimality in the general unrestricted case remained open. Lastly, we show how to evaluate the average acceleration ratio of the class of exponential strategies in the setting of n problem instances and m parallel processors. This is a broad class of schedules that tend to be either optimal or near-optimal, for several variants of the basic problem.
Type de document :
Article dans une revue
Journal of Artificial Intelligence Research, Association for the Advancement of Artificial Intelligence, 2014, 51, pp.533-554. 〈10.1613/jair.4360〉
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https://hal.archives-ouvertes.fr/hal-01185110
Contributeur : Lip6 Publications <>
Soumis le : mercredi 19 août 2015 - 11:17:56
Dernière modification le : jeudi 11 janvier 2018 - 06:27:16

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Alejandro López-Ortiz, Spyros Angelopoulos, Angele M Hamel. Optimal Scheduling of Contract Algorithms for Anytime Problem-Solving. Journal of Artificial Intelligence Research, Association for the Advancement of Artificial Intelligence, 2014, 51, pp.533-554. 〈10.1613/jair.4360〉. 〈hal-01185110〉

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