Author: Robert Hyatt
Date: 18:58:32 09/18/01
Go up one level in this thread
On September 18, 2001 at 18:26:00, Uri Blass wrote: >On September 18, 2001 at 18:10:19, Robert Hyatt wrote: > >>On September 18, 2001 at 18:08:32, Robert Hyatt wrote: >> >>>On September 18, 2001 at 17:17:35, Uri Blass wrote: >>> >>>>On September 18, 2001 at 16:33:08, Robert Hyatt wrote: >>>> >>>>>On September 18, 2001 at 13:24:45, Uri Blass wrote: >>>>> >>>>>> >>>>>>Note that I said that computers can safely evaluate +2 if they do not see a >>>>>>positional advantage for the side with less pawns. >>>>>> >>>>>>Having a distant majority is a positional advantage. >>>>> >>>>>Not when hardly _any_ programs recognize it. >>>>> >>>>> >>>>>> >>>>>>I also think that Ed is right and today search solves usually the problem of >>>>>>missevaluating pawn majority. >>>>> >>>>>I disagree. If you enter into a series of captures, you might burn all your >>>>>search on the captures and have none left to see what the majority is going to >>>>>do. So you take the first step, and then you are committed. And every move >>>>>you make sees your score drop as you begin to sense the problem. By the time >>>>>the forced trades are done, you realize you are lost, as a king and pawns ending >>>>>can be searched incredibly deeply. >>>> >>>>Can you give a position that demonstates your point? >>>> >>>>Uri >>> >>> >>>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. The position could be adjusted to make a good test position probably. I was just trying to show (a) a position where a pawn up is lost if pieces are traded and (b) a position where you make the first move and are then committed with no way to back out, and you lose whether you back out or not once you step into the mess...
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