GTQ: A Language and Tool for Game-Tree Analysis

The search engines of high-performance game-playing programs are becoming increasingly complex as more and more enhancements are added. To maintain and enhance such complex engines is a challenging task, and the risk of introducing bugs or other unwanted behavior during modifications is substantial. In this paper we introduce the Game Tree Query Language (GTQL), a query language specifically designed for analyzing game trees. The language can express queries about complex game-tree structures, including hierarchical relationships and aggregated attributes over subtree data. We also discuss the design and implementation of the Game Tree Query Tool (GTQT), a software tool that allows efficient execution of GTQL queries on game-tree log files. The tool helps program developers to gain added insight into the search process of their engines, as well as making regression testing easier. Furthermore, we use the tool to analyze and find interesting anomalies in search trees generated by a competitive chess program.