Parallel Monte-Carlo Tree Search

  • Authors:
  • Guillaume M. Chaslot;Mark H. Winands;H. Jaap Herik

  • Affiliations:
  • Games and AI Group, MICC, Faculty of Humanities and Sciences, Universiteit Maastricht, Maastricht, The Netherlands;Games and AI Group, MICC, Faculty of Humanities and Sciences, Universiteit Maastricht, Maastricht, The Netherlands;Games and AI Group, MICC, Faculty of Humanities and Sciences, Universiteit Maastricht, Maastricht, The Netherlands

  • Venue:
  • CG '08 Proceedings of the 6th international conference on Computers and Games
  • Year:
  • 2008

Quantified Score

Hi-index 0.00

Visualization

Abstract

Monte-Carlo Tree Search (MCTS) is a new best-first search method that started a revolution in the field of Computer Go. Parallelizing MCTS is an important way to increase the strength of any Go program. In this article, we discuss three parallelization methods for MCTS: leaf parallelization, root parallelization, and tree parallelization. To be effective tree parallelization requires two techniques: adequately handling of (1) local mutexesand (2) virtual loss. Experiments in 13×13 Go reveal that in the program Mangoroot parallelization may lead to the best results for a specific time setting and specific program parameters. However, as soon as the selection mechanism is able to handle more adequately the balance of exploitation and exploration, tree parallelization should have attention too and could become a second choice for parallelizing MCTS. Preliminary experiments on the smaller 9×9 board provide promising prospects for tree parallelization.