Performance of ( D ; d ) - OM Search

In Opponent-Model search (OM search) perfect knowledge of the opponent's evaluation function is assumed. This knowledge may lead to the conclusion that the opponent intends to make an error in a given position. As a consequence the error may be exploited to the advantage of the player possessing the knowledge. In such an OM-search model, it is implicitly assumed that both players search to the same depth. The current paper describes a generalization of OM search, called (D; d)-OM search, in which the di erence of the search depth reached by both players is taken into account. The algorithm, the main characteristics and an analysis of the e ciency are given in detail. Moreover, a game-tree model including an opponent model is constructed. Finally, preliminary results are given using that model and using Othello.