In this paper a new method is described for move ordering, called the relative history heuristic. It is a combination of the history heuristic and the butterfly heuristic. Instead of only recording moves which are the best move in a node, we also record the moves which are applied in the search tree. Both scores are taken into account in the relative history heuristic. In this way we favour moves which on average are good over moves which are sometimes best. Experiments in loa show that our method gives a reduction between 10 and 15 per cent of the number of nodes searched. Preliminary experiments in go confirm this result. The relative history heuristic seems to be a valuable element in move ordering.
|Title of host publication||Computers and Games. CG 2004|
|Editors||H.J. van den Herik, Y. Björnsson, N.S. Netanyahu|
|Publisher||Springer, Berlin, Heidelberg|
|Publication status||Published - 1 Jan 2006|
|Series||Lecture Notes in Computer Science|