Author: Robert Hyatt
Date: 10:13:45 05/02/02
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On May 02, 2002 at 12:36:13, Peter Fendrich wrote: >Please don't try to solve these positions! >They are only intended to illustrate difficulties with the static exchange >evaluation (capture on e4). > >[D]1k6/1qp5/2b5/8/4P3/3Q4/8/3K4 b - - >My SEE function,with the help of the XRay function, correctly evaluates that >Bxe4 earns a pawn. The same function would detect that Bxe4 is no good if white >had bishop at c2. > >There are two different situations that my SEE can't detect because I didn't >like the extra cost to always try detect these rare cases. > >First, my Xray function doesn't care about Xrays through opposite colors. >[D]1k6/1qp5/2b5/8/4P3/3Q4/2B5/1b1K4 b - - >In this position my SEE wouldn't detect that Bxe4 earns a pawn. The XRay >function doesn't care about the bishop at b1. >Does your SEE functions try to solve that? No... It isn't hard to do, but at present when I remove a piece from the Swap() list, I only look for pieces of the same side behind it, which breaks this. However, I suspect this is so rare that it doesn't count... And rather than Bxe4 you can always play BxB first, then after the queen recaptures, Bxe4 wins the pawn outright... > >Secondly, my SEE doesn't try to evaluate where to start more than one piece of >the same type can capture at the same time. i.e. two Pawns, Bishops, Rooks or >Queens can capture at the same square. >[D]1k6/1b6/1pq3q1/8/4P3/8/1K2Q3/Q3R3 b - - >Here my SEE wouldn't know that Qc6xe4 is generally better than Qg6xe4. In the >first case it opens up for the bishop to recapture the black queen. In the >second case only the Q at c6 can recapture. >With the same arguments as above I didn't try to solve the rare case when the >same piece can capture. >Does your SEE functions take care of this one? > >Peter No and I don't think this one is important at all. At least not important enough to lose sleep over...
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