Title
Monte Carlo Tree Search for Asymmetric Trees.
Abstract
We present an extension of Monte Carlo Tree Search (MCTS) that strongly increases its efficiency for trees with asymmetry and/or loops. Asymmetric termination of search trees introduces a type of uncertainty for which the standard upper confidence bound (UCB) formula does not account. Our first algorithm (MCTS-T), which assumes a non-stochastic environment, backs-up tree structure uncertainty and leverages it for exploration in a modified UCB formula. Results show vastly improved efficiency in a well-known asymmetric domain in which MCTS performs arbitrarily bad. Next, we connect the ideas about asymmetric termination to the presence of loops in the tree, where the same state appears multiple times in a single trace. An extension to our algorithm (MCTS-T+), which in addition to non-stochasticity assumes full state observability, further increases search efficiency for domains with loops as well. Benchmark testing on a set of OpenAI Gym and Atari 2600 games indicates that our algorithms always perform better than or at least equivalent to standard MCTS, and could be first-choice tree search algorithms for non-stochastic, fully-observable environments.
Year
Venue
Field
2018
arXiv: Machine Learning
Mathematical optimization,Monte Carlo tree search,Observability,Search algorithm,Algorithm,Tree structure,Asymmetry,Benchmark (computing),Mathematics
DocType
Volume
Citations 
Journal
abs/1805.09218
1
PageRank 
References 
Authors
0.37
7
4
Name
Order
Citations
PageRank
Thomas M. Moerland1121.58
Joost Broekens234437.07
Aske Plaat352472.18
Catholijn M. Jonker42252241.53