Author: Robert Hyatt
Date: 15:23:09 09/16/98
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On September 16, 1998 at 18:16:31, John Coffey wrote: >Do programs use hash tables become they spend more time evaluating >the positions at the leaves than they do traversing the tree? > >How much overhead (CPU wise) do hash tables take? > >It seems to me that in the endgame you could have the same positions >arise multiple times, but in the middle game it would be rare. Has >anyone done any tests on this? > >John Coffey You apparently misunderstand the concept. "hash tables" (more correctly called transposition/refutation tables) store the results of searches at nodes inside the tree. so that if I search the move path Nf3 Nf6 Ng5 and search some more stuff deeper into the tree, when I get back to the position after these three moves I store the search result in the hash table. Then when search the moves Nh3 Nf6 Ng5 I reach the same position by different moves, but I find the result of the other search from this position and don't have to repeat it... There are other purposes, such as move ordering...
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