Advances in technology allow for increasingly deeper searches in competitive chess programs. Several experiments with chess indicate a constant improvement in a pro-gram's performance for deeper searches; a program searching to depth d + 1 scores roughly 80% of the possible points in a match with a program searching to depth d. In other board games, such as… (More)
Most parallel game-tree search approaches use synchronous methods, where the work is concentrated within a specific part of the tree, or at a given search depth. This article shows that asynchronous game-tree search algorithms can be as efficient as or better than synchronous methods in determining the minimax value. APHID, a new asynchronous parallel… (More)
This paper introduces the APHID (Asynchronous Parallel Hierarchical Iterative Deepening) game-tree search algorithm. APHID represents a departure from the approaches used in practice. Instead of parallelism based on the minimal search tree, APHID uses a truncated game-tree and all of the leaves of that tree are searched in parallel. APHID has been… (More)
This paper introduces the APHID (Asynchronous Parallel Hierarchical Iterative Deepening) game-tree search algorithm. An APHID search is controlled by a master and a series of slave processors. The master searches the rst d 0 ply of the game-tree repeatedly. The slaves are responsible for the bottom plies of the game-tree. The slaves asynchronously read work… (More)
This paper describes the inner workings of Keyano, a competitive Othello program that has achieved many top-three nishes in tournament play over the last ve years. The unique features of Keyano's midgame search routine, evaluation function and opening book are described in this paper.
This paper introduces the APHID (Asynchronous Parallel Hierarchical Iterative Deepening) game-tree search algorithm. An APHID search is a hierarchical search with a master controlling the top of the tree (d 0 ply), and the slaves searching the rest of the tree (d ? d 0 ply). The slaves asynchronously read work lists from the master and return score… (More)