Board maps and hill-climbing for opening and middle game play in shogi

Most strong game-playing programs use large, well tuned opening books to guide them through the early stages of the game. However, in shogi (Japanese chess) the classic approach of building a large opening book of known positions is infeasible. In this paper, we present a different approach for opening and middle game play in shogi. This method uses board maps that assign values to each square for each piece in a number of different formations. Hill-climbing is then used to guide pieces to optimal squares. We define board maps for defensive piece formations (castles), attacking formations (assaults) and for recognizing the type of opening position. Results show that using board maps in combination with hill-climbing significantly improves the playing strength of a shogi program. Furthermore, using maps for both castles and assaults is better than using only maps for castles.