Author: martin fierz
Date: 08:31:18 03/23/04
Go up one level in this thread
On March 23, 2004 at 10:14:05, Tord Romstad wrote: >On March 23, 2004 at 09:11:14, martin fierz wrote: > >>On March 23, 2004 at 04:35:49, Tord Romstad wrote: >>> >>>How do other engines evaluate this position? >> >>IMO this question is not the right question to ask. i think gothmog is rather >>good at giving up the exchange compared to other programs. > >That's a kind way to put it. :-) no, no. the exchange is valued too highly by most programs! >I would rather say that Gothmog values the exchange too little, and gives >it up too often. It sacrifices the exchange more often than any other engine >I have seen, and I am fairly sure it loses more games than it wins because >of this. > >>it's static eval for >>this position would be quite ok if the white bishop was on c1 for example, where >>it's mobility is apparantly only very little bigger (one more square to go to). >>therefore you have to ask not only what the static eval for the position is that >>you gave, but also for the one with the bishop on c1. many engines will give >>black a clear edge here because they are (too) materialistic. they will do this >>in both positions. the really interesting question is whether any engine can >>detect the HUGE difference between having the bishop on c1 or g1... > >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. >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)." 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). i will bet another beer (you owe me one IIRC) 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. let's see whether somebody answers my question above. if they do, you will be very much happier about gothmog's eval again. cheers martin
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