An evaluation function for Shogi
Grimbergen, R. (1997)
in: Game Programming Workshop in Japan '97, pp. 159--168, Kanagawa, Japan
Abstract
Shogi and chess are similar games. The aim in both games is to mate the
opponent's king. However, the main difference between shogi and chess is that
in shogi pieces taken from the opponent can be used again. This has important
consequences for
the evaluation function. In chess the material balance is vital for the
evaluation of a position while in shogi the evaluation of a
position is much more based on abstract concepts like bad piece
formations and danger to the king. In this paper a set of
features will be proposed that are vital for an evaluation function for shogi.
These features have been implemented in an evaluation function which is part
of a
complete shogi playing program. This evaluation function has been tested
by comparing its position assessment with the opinion of professional
players in 54 middlegame positions and 46 endgame positions from professional
games. The
evaluation function agreed with the expert opinion in 64 of these positions,
judging the middlegame positions a little better (67%) than the endgame
position (61%).