Node-expansion operators for the UCT algorithm

  • Authors:
  • Takayuki Yajima;Tsuyoshi Hashimoto;Toshiki Matsui;Junichi Hashimoto;Kristian Spoerer

  • Affiliations:
  • Japan Advanced Institute of Science and Technology;Matsue College of Technology;KDDI Research Laboratory;Japan Advanced Institute of Science and Technology;Japan Advanced Institute of Science and Technology

  • Venue:
  • CG'10 Proceedings of the 7th international conference on Computers and games
  • Year:
  • 2010

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Abstract

Recent works on the MCTS and UCT framework in the domain of Go focused on introducing knowledge to the playout and on pruning variations from the tree, but so far node expansion has not been investigated. In this paper we show that delaying expansion according to the number of the siblings delivers a gain of more than 92% when compared to normal expansion. We propose three improvements; one that uses domain knowledge and two that are domain-independent methods. Experimental results show that all advanced operators significantly improve the UCT performance when compared to the basic delaying expansion. From the results we may conclude that the new expansion operators are an appropriate means to improve the UCT algorithm.