Author: Robert Hyatt
Date: 20:37:03 06/23/02
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On June 23, 2002 at 19:39:48, Pham Hong Nguyen wrote: >My engine has not used pawn hash table yet. I use a special structure for pawns >and update it during making/unmaking moves. Now I am considering to implement >pawn?s hash table but see some dilemmas as following: > >- If I continue to use old way to update pawn?s structure, I can use pawn >structure anywhere (like checking open files for rooks, danger of passed pawns). >However, pawn?s hash will not help much. It will save just little time of >computing scores based on existing structure. >- For more effectiveness, I should implement a special function to update pawn >structure. That function will check/save from/to pawn?s table and return score >only. Therefore pawn?s hash will help more. However, I will not able to use that >structure anywhere outside that function and should use other methods if need >and will lose some performances. >- I don?t know any effective way to store and extract (to/from pawn?s hash >table) scores of same pawn structures and king positions but different from game >periods (middle game and endgame)? > >Could someone share experience about implementation of pawn hash table? Many >thanks. >PHN First, you probably don't want the king positions hashed into your pawn structure hash signature. Second, all you can really hash is simple pawn structure information, plus information that is expensive to compute (where are passed pawns, weak pawns, and the like) so that you can use this elsewhere without having to compute it, when you get a pawn hash hit... Note that the score you hash can _only_ depend on the positions of pawns. If you do _anything_ else you will introduce a bug, since the signature will not reflect the locations of anything but pawns...
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