Accuracy and Savings in Depth-Limited Capture Search

Capture search, an expensive part of any chess program, is conducted at every leaf node of the approximating game tree. Often an exhaustive capture search is not feasible, and yet limiting the search depth compromises the result. Our experiments confirm that for chess a deeper search results in less error, and show that a shallow search does not provide significant savings. It is therefore better to do an arbitrary depth capture search. If a limit is used for search termination, an odd depth is preferable. Final copy for the Int. J. of Man-Machine Studies submitted Dec. 1986 accepted July 1987