Multi-Player Alpha-Beta Pruning
نویسنده
چکیده
Korf, R.E., Multi-player alpha-beta pruning (Research Note), Artificial Intelligence 48 (1991) 99-111. We consider the generalization of minimax search with alpha-beta pruning to non-cooperative, perfect-information games with more than two players. The minimax algorithm was generalized in [2] to the maxn algorithm applied to vectors of n-tuples representing the evaluations for each of the players. If we assume an upper bound on the sum of the evaluations for each player, and a lower bound on each individual evaluation, then shallow alpha-beta pruning is possible, but not deep pruning. In the best case, the asymptotic branching factor is reduced to (1 + 4bv'~b-"s~-3)/2. In the average case, however, pruning does not reduce the asymptotic branching factor. Thus, alpha-beta pruning is found to be effective only in the special case of two-player games. In addition, we show that it is an optimal directional algorithm for two players.
منابع مشابه
On Pruning Techniques for Multi-Player Games
Max (Luckhardt and Irani, 1986) is the extension of the minimax backup rule to multi-player games. We have shown that only a limited version of alpha-beta pruning, shallow pruning, can be applied to a max search tree. We extend this work by calculating the exact bounds needed to use this pruning technique. In addition, we show that branch-and-bound pruning, using a monotonic heuristic, has the ...
متن کاملLeaf-Value Tables for Pruning Non-Zero-Sum Games
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 p...
متن کاملLast-Branch and Speculative Pruning Algorithms for Max"
Previous work in pruning algorithms for max" multi-player game trees has produced shallow pruning and alpha-beta branch-and-bound pruning. The effectiveness of these algorithms is dependant as much on the range of terminal values found in the game tree as on the ordering of nodes. We introduce last-branch and speculative pruning techniques which can prune any constantsum multi-player game tree....
متن کاملAlpha-Beta Pruning for Games with Simultaneous Moves
Alpha-Beta pruning is one of the most powerful and fundamental MiniMax search improvements. It was designed for sequential two-player zero-sum perfect information games. In this paper we introduce an Alpha-Beta-like sound pruning method for the more general class of “stacked matrix games” that allow for simultaneous moves by both players. This is accomplished by maintaining upper and lower boun...
متن کاملAlpha-Beta Pruning and Althöfer's Pathology-Free Negamax Algorithm
The minimax algorithm, also called the negamax algorithm, remains today the most widely used search technique for two-player perfect-information games. However, minimaxing has been shown to be susceptible to game tree pathology, a paradoxical situation in which the accuracy of the search can decrease as the height of the tree increases. Althöfer’s alternative minimax algorithm has been proven t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Artif. Intell.
دوره 48 شماره
صفحات -
تاریخ انتشار 1991