Abstract
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 to be invulnerable to pathology. However, it has not been clear whether alpha-beta pruning, a crucial component of practical game programs, could be applied in the context of Alhöfer’s algorithm. In this brief paper, we show how alpha-beta pruning can be adapted to Althöfer’s algorithm.
Highlights
The minimax algorithm remains today the most widely used game tree search technique for two-player perfect-information games
For a given board position, a game tree is built to some depth, a static board-evaluation function is applied to the leaf nodes, and evaluation values are propagated up the tree and used to estimate the evaluation of the root
A criticism of minimaxing is that because the evaluation function applied to the leaf nodes is itself an estimate rather than an exact measurement, evaluation errors introduced at the search frontier can become amplified as they are propagated up the tree, leading to an incorrect root evaluation
Summary
The minimax algorithm remains today the most widely used game tree search technique for two-player perfect-information games. For a given board position, a game tree is built to some depth, a static board-evaluation function is applied to the leaf nodes, and evaluation values are propagated up the tree and used to estimate the evaluation of the root. A criticism of minimaxing is that because the evaluation function applied to the leaf nodes is itself an estimate rather than an exact measurement, evaluation errors introduced at the search frontier can become amplified as they are propagated up the tree, leading to an incorrect root evaluation. As an alternative to conventional minimaxing, Ingo Althöfer’s [15] alternative minimax algorithm, which uses evaluation values of all nodes in the tree, rather than only leaf nodes, in the evaluation of the root, has been proven not to suffer from pathology. In the remainder of this paper, we show how full alpha-beta pruning can be adapted to Althöfer’s algorithm
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
