Shape-Keeping Technique and Its Application to Checkmate Problem Composition

The checkmate problem in Shogi (Japanese Chess) is a puzzle within the game itself. These puzzles have enjoyed a long play and have been the subject of centuries of analysis. The subject of this research is defining the aesthetic criteria of great Shogi problems, and finding new methods for composing interesting checkmate problems in Shogi. First we examine the results of previous studies of aesthetics in Shogi checkmate problems. For this purpose, we focus on the Proof Number Search algorithm and record the data while solving checkmate problems. We analyzed these data and we calculated the proof number related to the evaluation of the checkmate problem. Good checkmate problems have large proof numbers. Next, we present a new technique for automatic composition of checkmate problems in Shogi. This technique uses already existing checkmate problems in Shogi and develops them further. Finally, we can compose new checkmate problems which have bigger proof numbers than original ones. This work is not yet sufficient unto itself.