Author: Robert Hyatt
Date: 06:59:01 09/21/99
Go up one level in this thread
On September 20, 1999 at 18:36:42, Howard Exner wrote: >On September 20, 1999 at 14:42:27, Robert Hyatt wrote: > >> >>Here are a couple of examples: >> >> +---+---+---+---+---+---+---+---+ >> 8 | | | | | | | *K| | >> +---+---+---+---+---+---+---+---+ >> 7 | *P| *P| | | | *P| *P| *P| >> +---+---+---+---+---+---+---+---+ >> 6 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ >> 5 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ >> 4 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ >> 3 | | | | | | | P | | >> +---+---+---+---+---+---+---+---+ >> 2 | P | P | P | | | | P | | >> +---+---+---+---+---+---+---+---+ >> 1 | | | | | | | K | | >> +---+---+---+---+---+---+---+---+ >> a b c d e f g h >> >> >>(fen 6k1/pp3ppp/8/8/8/6P1/PPP3P1/6K1/ w) >> >>old (16.18 crafty) evaluates this as -36 (black is better) because of >>those two doubled kingside pawns. new crafty says +.36 because white has >>a potential outside passer on the c file, black can't force a passer without >>the king helping. Better... > >Black can force a passer here without the king's help. > Of course but he also gives black one in return, which was the point. My eval doesn't give anyone credit here. But the search returns a mate in 14 almost instantly. (mate in 14 for black winning) Remember, I am simply trying to recognize (positionally) winning positions. I don't think it is physically possible to force crafty into such a position with the king totally blocked behind a bishop that is totally blocked, etc. I'll accept that kind of error to get the real positions mostly right. :) Even an outside passed pawn doesn't always win. But it does most of the time, so that the eval term I have had for years has always been pretty accurate... >Try the below artificial (and illegal) example on crafty. It will test >whether black can force a passer without the king's help. It has that same pawn >configuration on the king's side. > >1kb5/1p1p1ppp/1P1P4/8/8/1p1p2P1/1P1P2P1/K1B5 w if you try to win the position I originally gave, if anybody wins, white wins, and white winning is pretty likely. Because my first moves as white will not have to worry about a black pawn running in, since the white king will stop it easily.
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