Analysis of Transposition Tables and Replacement Schemes

A set of experiments were designed to measure the enhancement to alphabeta search using refutation and transposition tables. Results indicate that the use of transposition tables can reduce the size of the game tree by as much as 95%, significantly improving the algorithmic performance of αβ search. Seven replacement schemes to handle collisions in transposition tables were proposed and their performance measured. Based on the results of the experiment it can be concluded that for large-sized tables all schemes perform nearly identically. Because of the probability of the collisions is inversely proportional to the size of the table, for smaller sizes two level replacement schemes outperformed the single-level implementations. Key Terms: computer chess, transposition tables, collisions, replacement schemes, alpha-beta search, refutation tables