The Implementation of Artificial Intelligence and Temporal Difference Learning Algorithms in a Computerized Chess Programme By James Mannion Computer Systems Lab Period 3

Abstract Searching through large sets of data Complex, vast domains Heuristic searches Chess Evaluation Function Machine Learning

Introduction Simple domains, simple heuristics The domain of chess Deep Blue – brute force Looking at moves before making the first Supercomputer Too many calculations Not efficient

Introduction (cont’d) Minimax search Alpha-beta pruning Only look 2-3 moves into the future Estimate strength of position Evaluation function Can improve heuristic by learning

Introduction (cont’d) Seems simple, but can become quite complex. Chess masters spend careers learning how to “evaluate” moves Purpose: can a computer learn a good evaluation function?

Background Claude Shannon, 1950 Brute force would take too long Discusses evaluation function 2-ply algorithm, but looks further into the future for moves that could lead to checkmate Possibility of learning in distant future

Background (cont’d) D.F. Beal, M.C. Smith, 1999 Temporal Difference learning Program spends 20,000 games learning the evaluation function Beats program that did not learn a function Shows that programs can make their evaluation functions better

Background (cont’d) David E. Moriarty, Riso Miikkulainen Evolutionary Neural Networks Othello Complex Strategies developed

Background (cont’d) Shiu-li Huang, Fu-ren Lin, 2007 Temporal Difference Learning Multi-Agent Bargaining Bargaining, while not necessarily adversarial, is similar to chess and other games.

Development Python Stage 1: Text based chess game Two humans input their moves Illegal moves not allowed

Development (cont’d)

Stage 2: Introduce a computer player 2-3 ply Evaluation function will start out such that choices are random

Development (cont’d) Stage 3: Learning Temporal Difference Learning Adjusts the weights of the evaluation function slightly based on gameplay Evaluation function updated each time a game is played

Testing Learning vs No Learning Two equal, random computer players pitted against each other. One will have the ability to learn Thousands of games Win-loss differential tracked over the length of the test By the end, the learner should be winning significantly more games.

References Shannon, Claude. “Programming a Computer for Playing Chess.” 1950 Beal, D.F., Smith, M.C. “Temporal Difference Learning for Heuristic Search and Game Playing.” 1999 Moriarty, David E., Miikkulainen, Risto. “Discovering Complex Othello Strategies Through Evolutionary Neural Networks.” Huang, Shiu-li, Lin, Fu-ren. “Using Temporal- Difference Learning for Multi-Agent Bargaining.” 2007 Russell, Stuart, Norvig, Peter. Artificial Intelligence: A Modern Approach. Second Edition