Proof Number Based Monte-Carlo Tree Search
This addresses game AI performance for domains like board games, but it is incremental as it builds on existing algorithms.
The paper tackled the problem of improving decision-making in game search by combining Monte-Carlo Tree Search (MCTS) and Proof-Number Search (PNS) into PN-MCTS, resulting in outperforming MCTS across multiple games with win rates up to 96.2% for Lines of Action.
This paper proposes a new game-search algorithm, PN-MCTS, which combines Monte-Carlo Tree Search (MCTS) and Proof-Number Search (PNS). These two algorithms have been successfully applied for decision making in a range of domains. We define three areas where the additional knowledge provided by the proof and disproof numbers gathered in MCTS trees might be used: final move selection, solving subtrees, and the UCB1 selection mechanism. We test all possible combinations on different time settings, playing against vanilla UCT on several games: Lines of Action ($7$$\times$$7$ and $8$$\times$$8$ board sizes), MiniShogi, Knightthrough, and Awari. Furthermore, we extend this new algorithm to properly address games with draws, like Awari, by adding an additional layer of PNS on top of the MCTS tree. The experiments show that PN-MCTS is able to outperform MCTS in all tested game domains, achieving win rates up to 96.2% for Lines of Action.