Author: Michel Langeveld
Date: 05:44:45 02/21/04
Go up one level in this thread
On February 21, 2004 at 08:37:50, Uri Blass wrote: >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 I spoke with Andrew about this in ICC and said something similiair. Not a normal task for QSearch to pick this up. But on the other hand if you think about it if an engine is capable to find Qh4 in a cheap way then this engine is in on the right path to become a tactical monster. [D]r2q1rk1/ppp4p/2n5/4ppN1/Q7/P2P2P1/1P2PPbP/R4RK1 w - - In this position a queen on h7 is mate. All moves that makes it possible to get a queen on h7 are interesting. With this reasoning Qh4 can be found.
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