Author: Uri Blass
Date: 05:37:50 02/21/04
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On February 21, 2004 at 08:23:59, Andrew Wagner wrote: >The position is [D]r2q1rk1/ppp4p/2n2b2/3bppp1/Q7/P2PBNP1/1P2PPBP/R4RK1 w - - 0 1 > >The idea of course is to find Bxg5 Bxg5 Nxg5 Bxg2 (Qxg5 Bxd5) Qh4!(threatening >mate while defending the knight) 1-0 > >and I'm sure most engines would find that very easily. The question is a.) Is >this a move quiescence should find, and how? and b.) How do you keep from >pruning this move via SEE or MVVLA if you have them implemented? This move is not a move that qsearch should find because qsearch does not search nothing like that. Qh4 is not a capture or check and qsearch has not enough depth to find threats of mate in 1. Even after Qh4 programs should not evaluate the position as better for white by qsearch because black is a piece up for a pawn and the black king is not in check so by stand pat programs return beta and programs need to search at least one ply more in the main search to find the mate(it may be even more than one ply more because after Bxf1 your program may prune Qxh7# as a capture that is not good enough to get the score above beta and even after Bxf1 Qxh7# if your program does not evaluate mates it may not see the mate and need another ply to see that the king is captured). Note that in the case of movei I think that one ply after Qh4 is enough because it prunes no captures in the first ply of the qsearch and finding if the position is mate is part of the evaluation. Uri
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