Bascially it's the taks of encoding the rules of the game and then, of course, find an algorithm to find the best solutions.
This is why some of them get pretty confused when doing unusual things, which was a winnig approach in the older generations of chess enginges. Most of the chess engines rely on approved chess theortical investigations and have quiet a large bibliothek of them to evalute to first 12 moves of a game.
Chess Program Algorithm, free chess program algorithm software downloads.
