Author: Tord Romstad
Date: 09:22:16 03/23/04
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On March 23, 2004 at 11:31:18, martin fierz wrote: >On March 23, 2004 at 10:14:05, Tord Romstad wrote: > >>One of the really embarassing things about Gothmog's eval of this position >>is that it doesn't even consider the bishop on g1 to be a bad biship. My >>bad bishop eval is based on the number of *blocked* pawns on squares of the >>bishop's colour. In the position we discuss, there are only two such pawns >>(on e3 and g3). Therefore Gothmog thinks that the g1 bishop isn't really >>that bad. It has limited mobility, but it should be easy to relocate it >>to a better square. > >perhaps you should change your definition a bit. the pawn on f2 is virtually >blocked too, and the pawn on c4 is rather blocked and with it the one on c3. in >any case, the f2-pawn should be recognizable as blocked. >to evaluate my bishops, i use a sum of c1*(blocked pawns on that color) + >c2*(unblocked pawns on that color). i think that is a better way of doing it. >still it's not good, because as said, the g1-bishop would be just fine on a3 or >on f4. Thanks for the suggestions. You are probably right, I should have a look at my bad bishop code. >>As so often, Gothmog's eval proves to be the worst of them all. >no!!! as i said you asked the wrong question! you didn't even answer the right >question yourself, and all others won't answer it either as i know them... the >right question is: > >*************************************************************** >"please give me your static eval with bishop on g1, c1 and a3". >*************************************************************** > >my answer is "-0.49 (g1), -0.51(c1), -0.35(a3)." ... and my answer is "+0.24 (g1), +0.18 (c1), +0.31 (a3)". >as you can see, my answer is always about the same, and for example ridiculous >in that g1 is preferred over c1 (reason: the rook's mobility is smaller for >Bc1). Same thing here, as you can see from my numbers. >i will bet another beer (you owe me one IIRC) I do. :-) >that most of the people who >answered your post (and of who you think they are evaluating this better) have >similar problems. e.g. the position with the bishop on c1/a3 is roughly equal >(well, with the Ba3 you in fact immediately win a pawn, but just philosophically >speaking, white has little to fear with a pawn for the exchange and the bishop >pair) and all those guys who gave a big negative score for white will still be >giving a big negative score for white (because nobody is realizing that the >g1-bishop is the big problem, they just think exchange=2 pawns), and gothmog's >eval will be the superior one. Do you think that white has the advantage with the bishop at c1? Exchange=1.75 pawns in Gothmog, by the way. Tord
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