Expected Work Search: Combining Win Rate and Proof Size Estimation

Expected Work Search: Combining Win Rate and Proof Size Estimation

Owen Randall, Martin Müller, Ting-Han Wei, Ryan Hayward

Proceedings of the Thirty-Third International Joint Conference on Artificial Intelligence
Main Track. Pages 7003-7011. https://doi.org/10.24963/ijcai.2024/774

We propose Expected Work Search (EWS), a new game solving algorithm. EWS combines win rate estimation, as used in Monte Carlo Tree Search, with proof size estimation, as used in Proof Number Search. The search efficiency of EWS stems from minimizing a novel notion of Expected Work, which predicts the expected computation required to solve a position. EWS outperforms traditional solving algorithms on the games of Go and Hex. For Go, we present the first solution to the empty 5x5 board with the commonly used positional superko ruleset. For Hex, our algorithm solves the empty 8x8 board in under 4 minutes. Experiments show that EWS succeeds both with and without extensive domain-specific knowledge.
Keywords:
Search: S: Heuristic search
Search: S: Applications
Search: S: Game playing