{"type":"ScholarlyArticle","title":"Leaf-Value Tables for Pruning Non-Zero-Sum Games","authors":[{"name":"Nathan R. Sturtevant","slug":"nathan-r-sturtevant","given":"Nathan R.","family":"Sturtevant","affiliation":""}],"abstract":"Algorithms for pruning game trees generally rely on a game being zero-sum, in the case of alpha-beta pruning, or constant-sum, in the case of multi-player pruning algorithms such as speculative pruning. While existing algorithms can prune non-zero-sum games, pruning is much less effective than in constant-sum games. We introduce the idea of leaf-value tables, which store an enumeration of the possible leaf values in a game tree. Using these tables we are can make perfect decisions about whether or not it is possible to prune a given node in a tree. Leaf-value tables also make it easier to incorporate monotonic heuristics for increased pruning. In the 3-player perfect-information variant of Spades we are able to reduce node expansions by two orders of magnitude over the previous best zero-sum and non-zero-sum pruning techniques.","doi":null,"url":"https://ijcai.org/proceedings/2005/109","pdf":"https://ijcai.org/proceedings/2005/0109.pdf","markdown":"https://ijcai.org/proceedings/2005/109.md","bibtex":"https://ijcai.org/proceedings/2005/bibtex/109","volume":{"slug":"2005","title":"Proceedings of the Nineteenth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2005","url":"https://ijcai.org/proceedings/2005/","year":2005,"location":"Edinburgh, Scotland, UK","dates":"","editors":"","isbn":"","publisher":"International Joint Conferences on Artificial Intelligence","doi_prefix":""},"section":null,"track":"","number":109,"pages":{"first":317,"last":322},"keywords":[],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}