Author: blass uri
Date: 23:10:36 02/04/99
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On February 05, 1999 at 00:28:11, James B. Shearer wrote: >On February 03, 1999 at 10:15:37, Robert Hyatt wrote: > >>On February 02, 1999 at 00:24:59, James B. Shearer wrote: >> >>>On January 31, 1999 at 10:43:10, Robert Hyatt wrote: >>> >>> >>>> >>>>No idea why it takes 16 plies however... but I'll look... >>>> >>> >>> A big part of the reason is crafty 16.3 is far too optimistic about g5. >>>This can lead to the positions like that shown below which crafty scores -2.35. >>>This is quite optimistic considering that material is even and the position is a >>>dead draw. Crafty 15.15 scores this position -1.19 (see below) which is still >>>optimistic but better. >>> >> >> >> >>I agree with the evaluation, in that if anybody wins, black wins. The >>protected passed pawn completely limits white's king to a few squares. >>But the fact that black's king is 'locked out' is an issue, which i try to >>resolve via search rather than by evaluation. On a normal machine, it can >>get to 16 plies very quickly and discover that it can force entry by pushing >>the other pawn... but it needs the depth to 'see' this rather than trying >>to 'evaluate' this... > > How can you resolve the locked out king by search? The position will >continue to score 2.35 or so until the 50 move or 3 rep rules kick in. This >means that to select h4 in preference to g5 (which leads to positions like this) >crafty must see more than that h4 is good, it must see that it is better than >the 2.35 (actually 1.71) it is incorrectly scoring g5 at. This takes much >longer than if the g5 positions were more accurately evaluated. Too long for >fitter so I drew a lost game. I think 15.15 would have won. > James B. Shearer I think that you cannot decide by one position if the change in the evaluation was in the right direction. I saw many cases when the passed pawn is important and the new crafty may find a win by transition to these pawn endings. Uri
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