Author: Ricardo Gibert
Date: 21:44:35 08/04/99
Go up one level in this thread
On August 04, 1999 at 23:29:12, Robert Hyatt wrote: >On August 04, 1999 at 21:04:00, Ricardo Gibert wrote: > >>On August 04, 1999 at 20:08:41, Robert Hyatt wrote: >> >>>On August 04, 1999 at 17:32:51, Ricardo Gibert wrote: >>> >>>>On August 04, 1999 at 16:30:38, Robert Hyatt wrote: >>>> >>>>>On August 04, 1999 at 14:40:31, KarinsDad wrote: >>>>> >>>>>>On August 04, 1999 at 14:09:18, Bruce Moreland wrote: >>>>>> >>>>>>> >>>>>>>On August 04, 1999 at 12:16:52, Dann Corbit wrote: >>>>>>> >>>>>>>>As a 'for instance': >>>>>>>> >>>>>>>>Suppose that on promotion, a program sees that it can promote to a knight >>>>>>>>instead of a queen, and get a king fork, taking a bishop, followed by a queen >>>>>>>>fork, taking the other bishop. In such a case, it might evaluate: >>>>>>>> -pawn+knight+bishop+bishop+two_bishop_bonus+(minor positional goo) >>>>>>>>verses >>>>>>>> -pawn+queen >>>>>>>>and get something a fraction more valuable than a queen. But down the road I >>>>>>>>would rather have the queen than a knight and remove the two bishops. >>>>>>>> >>>>>>>>How do programs deal with this? >>>>>>> >>>>>>>You are really saying you'd rather have a queen against two bishops than be a >>>>>>>knight up, right? >>>>>>> >>>>>>>bruce >>>>>> >>>>>>Actually, assuming an equal game, it is a preference of being up a queen for a >>>>>>pawn as opposed to being up a knight and two bishops for a pawn. >>>>>> >>>>>>Of course, decisions like these are always based off of the actual position, but >>>>>>here is a comment Kasparov made just the other day on Ponomariov - Al Modiakhi >>>>>>in round 1 of the championship: >>>>>> >>>>>>"Looking at Ponomariov's 7.Be3 with 8.Bb6 I have sensed chess of the very >>>>>>distant future. With my limited knowledge of the game I would consider 3 minor >>>>>>pieces in such position much better than Queen+pawn". >>>>>> >>>>>>So, there are obviously positions where having 3 minors is better than having >>>>>>the queen. >>>>>> >>>>>>KarinsDad :) >>>>> >>>>> >>>>>I think that in almost _all_ cases, three minors pieces are better than a >>>>>single queen.. and most games I have seen where this happens are wins for the >>>>>three minors. I don't like two minors and 3 pawns vs a queen however, unless >>>>>maybe if the pawns are all on the 6th rank or farther along. :) >>>> >>>>I felt pretty sure about this too, but I analyzed with Jack Peters a particular >>>>position and came away with idea that it was a lot closer than I thought and >>>>that subjective factors have a big impact. I still prefer the 3 pieces, but now >>>>I am more careful. The 3 pieces don't organize themselves very quickly, but the >>>>Q is relatively much faster in this respect. It depends very much on the >>>>position. >>>> >>>>Related to this topic is R+P+P vs B+N. You have indicated that you set this as >>>>equal. At first I thought this was a mistake, but then I thought about it and >>>>this may be right for chess playing programs, since they are not sufficiently >>>>effective in getting the rook into play. As a human, I use R+P < B+N < R+P+P. I >>>>believe this is the "normal" evaluation. R+P+P = B+N is a practical choice for >>>>computers. Of course subjective factors must be considered. >>> >>> >>>I have done that for a long time... but IM Larry Kaufman published an article >>>in Chess Life (not about computers particularly) about such material >>>imbalancess, and he concluded after looking at a lot of games, that two pieces >>>are about equal to R+P+P. Of course, if the two pawns are on the 7th, that >>>goes out the door, naturally... or if they are connected passers that can roll >>>quicker than the two pieces + the king can mobilize to win them... >> >>That is what he may have said, but he is going against the opinion of a lot of >>strong players all the same. In the endgame for example, Reuben fine states that >>R+P vs 2 minors is a draw, with more pawns on both sides it is still normally >>drawn, while R+P+P vs 2 minors always win. His use of "always" pre-supposes a >>"normal" position. >> >>It's true, before the endgame, comes the middlegame, so the side with 2 minors >>MUST play very energetically to avoid loss. The side with the 2 minors is in >>trouble. It is very possible to get compensation, since it is often not so easy >>to activate the rook in the middle game. >> >>You should change your eval for the endgame at least. > > >I think this is just another case where Fine is wrong. Larry's results were >based on studying games between top players, and looking at games with a >specific material imbalance, and then determining the win/lose/draw ratio for >each side. He concluded, based on actual GM play, that two minors vs a rook and >pawn is a significant advantage... and that this advantage holds until it >becomes a rook and two pawns vs the minor, then it becomes 'equal'. That R+P+P has an advantage over B+N is undeniable. > >Again, based on previous games GM vs GM without computers in the loop... That >wasn't really news as most everyone considers B+N vs R+P to be bad for the R+P >side (which is why such trades on f2/f7 are not played very often in high-level >chess games.) He found other interesting things as well and published them in >his article in CL.
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