Judgment of Static Life and Death in Computer Go Using String Graph

A String Graph(SG) and Alive String Graph(ASG) were defined to facilitate a static analysis of completed and counted games of Go. For the judgment of life and death, rules are applied to the situation where a stone is included and not included, and these rules are defined as a String Reduction (SR), Empty Reduction (ER), Edge Transform (ET), and Circular Graph (CG) when the stone is not included, and a Dead Enemy String Reduction (DESR) and Same Color String Reduction (SCSR) when the stone is included. Whether an SG is an ASG or not is then determined using these rules. The performance of the proposed method was tested using a problem set of games played by professional players, and all the games had been played to completion and counted. The experiment determined the error on the judgment of life and death. The test was performed on the final positions of the 20 games. The total number of stones was 5,367 and the number of strings was 772. The experimental results produced a very low error ratio for the judgment of static life and death, where the error ratio for the stones was 0.18% and that for the strings was 1.16%.