Author: Robert Hyatt
Date: 15:19:05 08/20/03
Go up one level in this thread
On August 20, 2003 at 07:36:37, Bo Persson wrote: >On August 19, 2003 at 08:07:07, Uri Blass wrote: > >>On August 19, 2003 at 08:05:39, Uri Blass wrote: >> >>>On August 19, 2003 at 07:43:08, Bo Persson wrote: >>> >>>>On August 19, 2003 at 06:19:59, Joost Buijs wrote: >>>> >>>>> >>>>>To me it looks wrong to skip losing captures from the quiescence search if the >>>>>losing captures are determined by a SEE that is wrong in some cases, e.g. pinned >>>>>pieces. If you use the SEE for move ordering purposes only this problem doesn't >>>>>exist. >>>> >>>>But it is always only an approximation, you just want it to be good enough to >>>>avoid flat out blunders. >>>> >>>>In a position like this >>>> >>>>[D]8/1p6/r1r5/8/8/8/8/R1R5 w - - 0 1 >>>> >>>>SEE will believe that the black rooks are both defended, but they are not. This >>>>is not a "pin", but an "overload" which is still missed. You just can't get it >>>>all (cheap). >>>> >>>> >>>>Bo Persson >>> >>>They are defended. >>> >>>Rxa6 Rxa6 >>> >>>if you want a better example then it is better to put a pawn at b6 and not only >>>at b7. >>> >>>Uri >> >>It is still wrong because Rxa6 Rxc1 >> >>It is better to put 2 knights and not 2 rooks to show that SEE may miss a good >>capture by white. > >Yes, you are right. My point was that if SEE is used to resolve captures on a >specific square, you miss the fact that a single piece can be involved in >several of these "shoot outs". In real play it often cannot, at least not >simultaneously. > >That another piece might be pinned doesn't make that much of a difference. > >Bo Persson > > I think that overloaded pieces, and pins, both contribute to the inaccuracy of SEE. I've handled pins in the past, but I don't now. I've never tried overloaded pieces as it is too complicated to figure out that "if I capture here with this piece, then I lose material over _there_ because I have one less defender than I need now." >> >>Uri
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