Author: martin fierz
Date: 16:48:16 09/06/02
Go up one level in this thread
On September 06, 2002 at 18:44:28, Uri Blass wrote: >On September 06, 2002 at 18:18:24, martin fierz wrote: > >>On September 06, 2002 at 12:14:00, Robert Hyatt wrote: >> >>>On September 06, 2002 at 10:56:54, Uri Blass wrote: >>> >>>>On September 06, 2002 at 07:23:15, Yuriy Lyapko wrote: >>>> >>>>>Which chess engine will see that Rb1 is winning in this position? >>>>> >>>>>[D] b4bk1/p2p4/p1p1p2p/P1P1Pp1P/3P3p/2N4N/1r3PP1/4R1K1 w - - >>>>> >>>>>Best regards, >>>>>George >>>> >>>>Movei0076 can see a small advantage for white with Rb1(p850,32 Mbytes hash) >>>>in less than 10 minutes. >>>> >>>>I imagine that stronger engines can find it faster. >>>> >>>>scores at the last iterations(from white point of view): >>> >>> >>>I don't make any claims about being "stronger" or "weaker" than much of >>>anything, but Rb1 is the _only_ move Crafty considers. >>> >>>It isn't going to like white's position, of course, until it sees white >>>winning material, which suggests that the bishop scoring needs more control >>>on the lack of mobility in this position. >>> >>>> >>> >>>The score starts out at -1.0 (good for black) and drops to about -.5 quickly. >>> >>>Which is totally wrong. >>> >>>Although, as I have said before, I don't think the _score_ is as important >>>as the move. Crafty obviously feels that the rooks need to go, which is the >>>right idea here. >> >>haven't you also said before that "right move for wrong reason" is worth little >>(i would agree with that)? you can always imagine crafty going for this position >>as black from something different thinking that it's fine here (example: remove >>those rooks, place black Nd5, white Bc3, white Nc3->e2 - now Nxc3 would be a >>really bad move...)- which is not the case. >> >>i'm saying right move for wrong reason since it seems to me that black would win >>a pawn if white doesn't exchange the rook (at least, black to move wins a5 with >>Rb3-a3. 1. Ra1 fails to Rc2-d2 (or if Nb1, Rc4)). > >It seems to me that black does not win a pawn because after Rb3-a3 white can >play Rb1 and if Rxa5 Rb8 and black lose the bishop a8. you are right! i should have consulted fritz first, but i just wrote that looking at the diagram. but the consultation does say that after "any move" like Nf4, as you suggest, white cannot trade rooks any more after Be7, because then he really loses a pawn (on a5). so the position still has a problem: the engine only has to recognize that black's rook is much more active, and therefore worth more than white's rook to play 1. Rb1 - since it can't exchange the rook any more after ...Be7. it does not have to understand anything about the following endgame - like crafty, which thinks black is better there (fritz gives +1.7 after Rb1 BTW; much better!). so i still think that the position is bad, because an engine can play the right move for the "wrong" reason (not that exchanging the opponent's most active piece is a "bad" reason. but the position was supposed to test the understanding of the NN-BB position - which it doesnt necessarily). aloha martin > >I believe that white is not worse after a move like Nf4. > >After Nf4 movei says 0.14 pawns for white > >19 -14 749525 1238949625 f8e7 f4e2 e7d8 e1a1 g8f7 f2f3 a8b7 g1f2 f7e8 f2e3 d8c7 >a1a3 e8f7 a3a4 f7e7 e2f4 b2b3 e3d3 e7f7 > >Uri
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