Increasing tree search efficiency for constraint satisfaction problems

  • Authors:
  • Robert M. Haralick;Gordon L. Elliott

  • Affiliations:
  • Electrical Engineering Dept., Computer Science Dept., Virginia Polytechnic Institute and State University, Blacksburg, Virginia;Electrical Engineering Dept., Virginia Polytechnic Institute and State University, Blacksburg, Virginia

  • Venue:
  • IJCAI'79 Proceedings of the 6th international joint conference on Artificial intelligence - Volume 1
  • Year:
  • 1979

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Abstract

In this paper we explore the number of consistency checks made by a tree search in order to solve binary constraint satisfaction problems. We show analytically and experimentally that the two principles of first trying the places most likely to fail and remembering what has been done to avoid repeating the same mistake twice improve the standard backtracking search. We experimentally show that a lookahead procedure called forward checking (to remember the future) which employs the most likely to fail principle performs better than standard backtracking, Ullman's, Waltz's, Mackworth's, and Haralick's discrete relaxation in all cases tested, and better than Gaschnigs backmarking in the larger problems.