The best chess machines are competitive with the best humans, but generate millions of positions per move. Their human opponents, however, only examine tens of positions, but search much deeper along some lines of play. Obviously, people are more selective in their choice of positions to examine. The importance of selective search was first recognized by (Shannon 1950). Most work on game-tree search has focussed on algorithms that make the same decisions as fullwidth, fixed-depth minimax. This includes alpha-beta pruning (Knuth & Moore 1975), fixed and dynamic node ordering (Slagle & Dixon 1969), SSS* (Stockman 1979), Scout (Pearl 1984), aspiration-windows (Kaindl, Shams, & Horacek 1991), etc.
Jan-10-2006, 02:59:26 GMT