H. G. Muller wrote on Sat, Oct 31, 2009 10:14 PM UTC:
The defensive pieces required a new approach in material evaluation, in my Xiangqi engine HaQiKi D. Rather than having a fixed value, their value is strongly dependent on the attacking material the opponent has. To implement that I use a material table that is indexed by the number of attacking pieces of each type for one side, and the number of defensive pieces of the other side.
In my simpler engine MaxQi (a dedicated version of Fairy-Max that can only play Xiangqi) I just use fixed piece values, and then itregularly happens that it converts its entire advantage to defensive pieces, thinking it is 800 centi-Pawn ahead, while in fact it has zero winning chance...