Author: Michael Henderson
Date: 21:37:19 09/20/04
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On September 21, 2004 at 00:15:42, Stuart Cracraft wrote: >On September 20, 2004 at 00:56:26, Michael Henderson wrote: > >>>>1. When you make a two-square pawn move, and the opponent cannot make an ep >>>>capture, do you hash-xor the "target" ep square in the hash table? >>> >>>Currently no special handling is done for the hash table in regards to >>>enpassant. That information is not recorded in any way. >> >>What I meant to say was do you hash in any ep target stuff into the hash key >>when you make a two-square pawn move, whether opponent can capture ep or not? >> >>Michael > >I don't do this and hadn't considered it. > >What side effects would you expect from the absence of this? consider two positions: A, and B. Positions A and B are identical in every respect but en-passant availability. Position A has a white pawn at e4 and a black pawn at d4. In position B white has just played e2e4 and black has a pawn at d4 -- so en passant capture. Now Search(): Then black comes to position A --does a search, whatever-- and finally hash stores. At some other node in the tree, black comes to position B and uses position A from the hash table to cutoff that node. That does not take into account any ep captures you have at position B, so your search can screw up. Michael
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