Author: Robert Hyatt
Date: 21:26:46 02/23/04
Go up one level in this thread
On February 23, 2004 at 23:20:15, Andrew Wagner wrote: >On February 23, 2004 at 23:05:58, Robert Hyatt wrote: > >>On February 23, 2004 at 18:52:36, Geoff Westwood wrote: >> >>>Hi >>> >>>I was perusing the latest table of results, Crafty's static eval of 2 of the >>>passed pawn positions were interesting. >>> >>>Assuming I havent made a mistake in the cutting and pasting >>> >>>Position 1 >>>8/4k3/8/7P/1P6/3p4/4p3/4K3 b - -; id "PP-00004" >>> >>>[D]8/4k3/8/7P/1P6/3p4/4p3/4K3 b - - >>> >>>Crafty reckons this is +4.8 (good for white). This is rather clever as although >>>the black king could catch either of the white passed pawns, it cannot stop >>>both. Also blacks 2 advanced pawns cant do anything as the white king gobbles >>>them up easily. Only Crafty and Tinker understand this position statically. Any >>>tips on what the algorithm is to sort this one out ? >> >> >>This is the idea I have reported here before, pointed out (demanded to be fixed >>in fact) by a GM friend of mine. The idea is that the two separated pawns are >>better than the two connected passers. The king stops the two connected passers >>easily until the enemy king supports them, meanwhile the split passers walk on >>in... >> >> > >>> >>> >>>Position 2 >>>8/P5p1/4P3/8/2k5/2P1pb2/8/4K3 b - -; id "PP-00005" >>> >>>[D]8/P5p1/4P3/8/2k5/2P1pb2/8/4K3 b - - >>> >>>Crafty reckons that this is -7.16 (won for black ??) >> >>This one it just gets wrong. It is fixable as the pawns are so advanced that >>one promotes, decoys the bishop, then the other promotes. At present, the >>search has to resolve this but it only takes a couple of plies..... >> >>> >>>Firstly is this a typo should it be +7.16 ? Surely this position is won for >>>white as the bishop cannot stop both pawns again. >>>If not a typo Crafty seems to be statically evaluating this quite badly, maybe >>>the clever eval in the previous position is flawed ? Or I have got my +/- signs >>>confused. >> >>The previous one it gets right, this one it just misses, but the miss is a >>result of the pieces. Take the pieces off and it gets it right most of the >>time, as it should. >> >> >> >> >Am I understanding correctly that you use a completely different eval function >in pure king/pawn endgames? E.g., surely in the first example, with a bunch of >pieces on the board, the connected passed pawns would be better, because the >pieces can catch the separate passed pawns whereas the connected once can defend >and advance themselves. Nope. I use one eval function. As material comes off, connected passers become weaker and split passers become stronger, until there are no pieces left, where the position above fits. > >>> >>> regards Geoff
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.