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Automatic Discovery and Exploitation of Promising Subproblems for Tabulation

  • Özgür Akgün
  • Ian P. Gent
  • Christopher Jefferson
  • Ian Miguel
  • Peter NightingaleEmail author
  • András Z. Salamon
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11008)

Abstract

The performance of a constraint model can often be improved by converting a subproblem into a single table constraint. In this paper we study heuristics for identifying promising subproblems. We propose a small set of heuristics to identify common cases such as expressions that will propagate weakly. The process of discovering promising subproblems and tabulating them is entirely automated in the tool Savile Row. A cache is implemented to avoid tabulating equivalent subproblems many times. We give a simple algorithm to generate table constraints directly from a constraint expression in Savile Row. We demonstrate good performance on the benchmark problems used in earlier work on tabulation, and also for several new problem classes.

Notes

Acknowledgements

We thank EPSRC for grants EP/P015638/1 and EP/P026842/1. Dr Jefferson holds a Royal Society University Research Fellowship.

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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Özgür Akgün
    • 1
  • Ian P. Gent
    • 1
  • Christopher Jefferson
    • 1
  • Ian Miguel
    • 1
  • Peter Nightingale
    • 1
    Email author
  • András Z. Salamon
    • 1
  1. 1.School of Computer Science, University of St AndrewsSt AndrewsUK

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