Author: Uri Blass
Date: 03:02:56 03/07/06
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On March 07, 2006 at 05:32:06, Richard Pijl wrote: > >>>You'll need to know that two connected passers beat a rook when progressed to >>>3rd rank (or one to 4 and 2) and the defending king is too far away. >>>You will not find it in reasonable time without this 'knowledge' in your passed >>>pawn evaluation if you are doing any kind of pruning (including nullmove >>>pruning) > >>This is not correct >> >>Movei find it in a few seconds without that knowledge and it certainly has >>pruning including null move pruning. > >ok. I was assuming that Rxb2 would not survive pruning, pushing it away at least >a few more ply, and the checks on 6-7th rank would push it even 6 ply minus >extensions further. Of course, pawn push extensions would help as well (The >Baron doesn't have those anymore). Seems that my assumptions were not correct. I only extend pawn push to the 7th and only in part of the cases. I also use verified null move pruning in the endgame based on David Omid's article and maybe it helps(the main advantage of verified null move pruning is not in detecting zugzwangs but in detecting threats earlier). Uri > >>This knowledge is not correct and based on this knowledge it may find Rxb2 also >>in the following diagram with the same PV. >> >> >>[D]8/7p/5k2/5p2/p1p2P2/Pr1p1K2/1P1R3P/8 b - - > >The key here is that the white king can help stop the black pawns, in the >original position its own pawn block the white's king access to the black pawn. >You removed it in this position so the defending king is close enough. The Baron >recognizes this and doesn't play the sac: I understand but this is not about distance of the king from the pawns. I assumed that the "defending king is too far away" is only about distance of the king from the pawns. I decided not to try to implement too complicated rules in the evaluation because I may have bugs if I try to do it and I believe that it is possible to earn more by search improvement so if I spend time on chess programming it is mainly about search. Uri
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