Author: Ricardo Gibert
Date: 21:47:24 08/04/99
Go up one level in this thread
On August 05, 1999 at 00:44:35, Ricardo Gibert wrote: >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. In the endgame of course. > >> >>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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