Author: Frank Schneider
Date: 02:51:36 12/30/98
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On December 30, 1998 at 04:29:49, Frank Schneider wrote: >Hi all programmers! > >I know it sounds very simple and unsound, but has anyone tried this: > >IF >- a position is found in the transpositiontable and >- it is an upper bound (all moves failed low) and >- the hashvalue is < alpha and >- hashdepth==depth-1 (tableentry from previous iteration) >THEN >only search the first n moves but do not store the result in the >transpositiontable. > >The idea is based on the observation that most nodes are either >a) nodes where only very few moves are searched until one causes a cutoff >or >b) nodes where all moves fail low. This is where the heuristic tries to >save some time. > >I just ran a first test with a mixed 100 positions testsuite (all searched 6 >ply) and got nice results: >- more correct moves (??) >- >20% less nodes > >I'll have a closer look at this.... Here are some more results: correct / nodes |n=infinite |n=15 |n=10 |n=5 ------------------------------------------------------------------------------- Standard #6 |23 / 8306851 |22 / 6616146 |25 / 6229700 |24 / 5852685 WAC #6 |256 / 13428654 |254 / 11575072 |253 / 10977570 |253 / 10987063 ------------------------------------------------------------------------------- n is the number of moves searched before cutting. Standard is a testsuite of 100 mixed positions (opening, middlegame, endgame, positional and tactical positions). #6 means every position was searched 6 iterations. I'll now try #7 but that may take some time... > >Have a Happy New Year, > >Frank
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