Author: martin fierz
Date: 12:55:36 03/23/04
Go up one level in this thread
On March 23, 2004 at 14:56:04, Mridul Muralidharan wrote: >On March 23, 2004 at 11:31:18, martin fierz wrote: > >>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 > > >Hmm , I think you lost a beer ;) not at all :-) the bet would have been "most of those who answered tord's post". of these, only richard has given the baron's eval for Bc1 / Bg1 - no real difference there. so up to now it's 1 who doesn't understand to 0 who understand. you came later and don't count :-) anyway, tord didn't accept the bet i think... >My engine evaluates the positions as follows : > >Bishop on g1 -> -1318 >Bishop on c1 -> -874 >Bishop on a3 -> -500 nice! cheers martin
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