Author: Uri Blass
Date: 07:16:36 09/19/01
Go up one level in this thread
On September 19, 2001 at 09:52:52, Robert Hyatt wrote: >On September 19, 2001 at 05:20:31, Bernhard Bauer wrote: > >>>>>>Here is a simple attempt: >>>>>> >>>>>>[D]2k5/1r6/3p1p2/n2p1p2/P2PpP2/R3P3/1BK5/8 b - - >>>>>> >>>>>>Here black has several moves to try, one which liquidates into a pawn up >>>>>>(but dead lost) ending. Rxb2 Kxb2 Nc4+ Ka2 Nxa3 Kxa3 and white is a pawn >>>>>>down, but winning easily. >>>>>> >>>>>>Once you start with Rxb2, you are committed. As if you try to back out and >>>>>>not play Nc4 and Nxa3, you are an exchange down. And if you do recover the >>>>>>material, you are dead lost. Add another such forced capture/recapture and >>>>>>you have burned 6 plies. You won't see white winning all the black pawns >>>>>>and winning. >>>>> >>>>> >>>>>Note that I don't say there are not better moves for black here. The point >>>>>was to show a move choice that commits you to a course of action that gets >>>>>worse and worse as you go deeper and deeper. >>>> >>>>I think that this is not a good example because white has an obvious positional >>>>advantage for programs(white has a passed pawn when black has 2 pawns on the >>>>same file for file d,f >>>> >>>>Uri >>> >>> >>>Pick any such position you want, where one side is a pawn up but the other is >>>winning. I have seen many. That is one example where if you trade, you lose. >>>And it is one example of where one extra pawn does _not_ mean you are winning. >>>Here it means you are losing and badly. >>> >> >>From a players point of view *white*is a pawn up, the a-pawn and therefor >>winning, just like Ed said. >>A player would not count the additional blocked black pawns. >>Kind regards >>Bernhard > > >Human, right. But set the position up and ask your favorite program which side >is winning with a simple static eval... I asked few program to give me their evaluation at depth 1 for this position [D]2k5/8/3p1p2/3p1p2/P2PpP2/n3P3/K7/8 w - - 0 3 CometB27 0.53 for white Junior7 0.20 for black. shredder5.32 0.18 for black. They clearly can see white's positional advantage by static evaluation and do not give +1 for black. I said that it is usually safe to evaluate as +2 pawn endgames when programs cannot see positional advantage for the side with less pawns. This is not the case in this example. Uri
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