Statistical Feature Combination for the Evaluation of Game Positions

This article describes an application of three well-known statistical methods in the field of game-tree search: using a large number of classified Othello positions, feature weights for evaluation functions with a game-phase-independent meaning are estimated by means of logistic regression, Fisher's linear discriminant, and the quadratic discriminant function for normally distributed features. Thereafter, the playing strengths are compared by means of tournaments between the resulting versions of a world-class Othello program. In this application, logistic regression - which is used here for the first time in the context of game playing - leads to better results than the other approaches.Comment: See http://www.jair.org/ for any accompanying file

A Survey of Monte Carlo Tree Search Methods

Monte Carlo tree search (MCTS) is a recently proposed search method that combines the precision of tree search with the generality of random sampling. It has received considerable interest due to its spectacular success in the difficult problem of computer Go, but has also proved beneficial in a range of other domains. This paper is a survey of the literature to date, intended to provide a snapshot of the state of the art after the first five years of MCTS research. We outline the core algorithm's derivation, impart some structure on the many variations and enhancements that have been proposed, and summarize the results from the key game and nongame domains to which MCTS methods have been applied. A number of open research questions indicate that the field is ripe for future work

An intelligent Othello player combining machine learning and game specific heuristics

Artificial intelligence applications in board games have been around as early as the 1950\u27s, and computer programs have been developed for games including Checkers, Chess, and Go with varying results. Although general game-tree search algorithms have been designed to work on games meeting certain requirements (e.g. zero-sum, two-player, perfect or imperfect information, etc.), the best results, however, come from combining these with specific knowledge of game strategies. In this MS thesis, we present an intelligent Othello game player that combines game-specific heuristics with machine learning techniques in move selection. Five game specific heuristics, namely corner detection, killer move detection, blocking, blacklisting, and pattern recognition have been proposed. Some of these heuristics can be generalized to fit other games by removing the Othello specific components and replacing them with specific knowledge of the target game. For machine learning techniques, the normal Minimax algorithm along with a custom variation is used as a base. Genetic algorithms and neural networks are applied to learn the static evaluation function. The five game specific techniques (or a subset of) are to be executed first and if no move is found, Minimax game tree search is performed. All techniques and several subsets of them have been tested against three deterministic agents, one non-deterministic agent, and three human players of varying skill levels. The results show that the combined Othello player performs better in general. We present the study results on the basis of four main metrics: performance (percentage of games won), speed, predictability of opponent, and usage situation

Playing Tic-Tac-Toe Using Genetic Neural Network with Double Transfer functions

Computational intelligence is a powerful tool for game development. In this paper, an algorithm of playing the game Tic-Tac-Toe with computational intelligence is developed. This algorithm is learned by a Neural Network with Double Transfer functions (NNDTF), which is trained by genetic algorithm (GA). In the NNDTF, the neuron has two transfer functions and exhibits a node-to-node relationship in the hidden layer that enhances the learning ability of the network. A Tic-Tac-Toe game is used to show that the NNDTF provide a better performance than the traditional neural network does

Neuroevolution in Games: State of the Art and Open Challenges

This paper surveys research on applying neuroevolution (NE) to games. In neuroevolution, artificial neural networks are trained through evolutionary algorithms, taking inspiration from the way biological brains evolved. We analyse the application of NE in games along five different axes, which are the role NE is chosen to play in a game, the different types of neural networks used, the way these networks are evolved, how the fitness is determined and what type of input the network receives. The article also highlights important open research challenges in the field.Comment: - Added more references - Corrected typos - Added an overview table (Table 1