Author: Uri Blass
Date: 00:49:31 04/13/03
Go up one level in this thread
On April 13, 2003 at 00:51:27, Robert Hyatt wrote: >On April 12, 2003 at 06:13:05, Uri Blass wrote: > >>On April 12, 2003 at 05:46:08, Jeremiah Penery wrote: >> >>>On April 12, 2003 at 04:22:57, Uri Blass wrote: >>> >>>>On April 12, 2003 at 01:44:26, Robert Hyatt wrote: >>>> >>>>>That has to be part of the evaluation. IE you have to know that you can >>>>>give the pawn up if your king is closer to the remaining pawns than the >>>>>opposing king is... >>>>> >>>>>I do that obviously... >>>> >>>>This has nothing to do with the pawn. >>>> >>>>You have to evaluate correctly the following position that can happen >>>>if you do not search deep enough >>>> >>>>[D]8/8/1K6/5p1p/4kP1P/6P1/8/8 w - - 0 6 >>>> >>>>I hope that movei will be able to see it after I add some knolwedge but the >>>>knowledge that is needed is not about passed pawns because there are no passed >>>>pawns in that position. >>> >>>Bob never said anything about passed pawns. >> >>He did in the post that started this thread: > >Yes, but that is just _one_ part. If you don't recognize a distant passer, >then you won't try to reach the starting position. Once you recognize distant >passers, you then have to correctly evaluate king position so that you will >give up the distant passer at the right time, even if you don't _know_ that you >will win by seeing it in the search. > >> >>http://www.talkchess.com/forums/1/message.html?292975 >> >>"This seems to be an example of an engine that misses the power of the "distant >>passed pawn". >> >>I agree that a lot of engines have problems in the evaluation but the problem >>is about not evaluating correctly king relative to the pawns and has nothing to >>do with evaluation of the "distant passed pawns". >> >>Uri > > >No, in that position it is about evaluating the distant passer. Later it is >about evaluating king position. Note that I talk only about the position that was posted and I do not claim that evaluating distant passed pawn is not important. My claim is that a program without knowledge about distant passed pawns but with knowledge about king relative to the pawns will have no problem in the relevant position. There are 2 cases: 1)The program does not search deep enouigh in order to see that the passed pawn is trapped In this case the program is not going to let the rook trade because it is easy to see that the position is at least equal if white does not allow the rook trade when allowing endgame. 2)The program see by search that the passed pawn is trapped. In that case evaluating king relative to pawns tells it that it is not good to capture the pawn. I think that 2 is easy to do for most program. Movei of today that has no knowledge of distant passed pawns or king relative to pawns needs some seconds on a slow hardware to find the relevant mistake and some minutes to avoid it. The reason that it needs some seconds to find the mistake is that without capturing the pawn it does not want to let black to trade the rooks. Uri
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