Abstract
In this paper we present an intelligent backtracking scheme for the independent and-parallel execution of Prolog. It is implemented for a distributed memory machine where an extended Warren Abstract Machine [1] is placed on each processor and can receive subgoals and spawn further subgoals to other processors.
The chosen scheme for the communication of bindings makes available additional run-time information which is incorporated into the execution. Our executor [2,3,4,5] is most notably derived from the execution schemes of Hermenegildo [6,7,8,9] and Lin [10] although both these other schemes are implemented for shared memory machines.
We present an incremental algorithm to support clause level intelligent backtracking. In our scheme intelligent backtracking will both select subgoal(s) attributable to the failure and prevent unnecessary re-execution of subgoals independent of the failure. We observe that a portion of the intelligent backtracking can be applied during forward execution and we introduce a notion of ‘intelligent cutting’.
The effectiveness of our execution scheme and intelligent backtracking is demonstrated by an implementation based on an array of transputer processors.
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© 1992 Springer-Verlag London
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Verden, A., Glaser, H. (1992). Intelligent Backtracking in And-Parallel Prolog. In: Darlington, J., Dietrich, R. (eds) Declarative Programming, Sasbachwalden 1991. Workshops in Computing. Springer, London. https://doi.org/10.1007/978-1-4471-3794-8_8
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DOI: https://doi.org/10.1007/978-1-4471-3794-8_8
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