Author: Uri Blass
Date: 18:51:09 01/19/01
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On January 19, 2001 at 21:33:08, John Merlino wrote: >On January 19, 2001 at 17:23:03, Scott Gasch wrote: > >>Hi all, >> >>Here's a pretty simple test position. This comes from the WAC suite... my >>engine does fairly well on this suite as a whole but seems blind to this >>solution. >> >>[D]8/7p/5k2/5p2/p1p2P2/Pr1pPK2/1P1R3P/8 b - - >> >>The solution is Rxb2 -- black's connected passers are unstoppable after the >>recapture. >> >>My program refuses to find this solution... even at 9 ply it misses it. The >>strange thing is that from the other side after Rxb2 it sees that white is toast >>very quickly... score dropping to -500 or so after about 1 second. >> >>My question is, of course, how this move is missed. I've tried kicking up the >>value of connected passers and passed pawns in general. I've tried adding a >>special rule to eval about connected passers on the 7th, on move, with control >>of a queening square. I've tried cutting back my futility margin in qsearch and >>always extending a full ply for checks (It usually extends only 3/4 ply for >>checks after the iteration depth). And still it does not find Rxb2. >> >>Even stranger is if I run a static eval with the two connected passers rolling >>towards the queening square after the rook exchange the eval puts black ahead! >>I can't seem to figure this out... either my pruning is too aggressive or there >>is some other bug in the engine...? >> >>I hope someone out there can give me a little advice. Thanks! >> >>Scott > >Just to make things difficult, Chessmaster 8000 seems to have this one's number, >AND it reports the correct move at ply 9, despite other postings here that have >stated that it should take somewhere between 12 and 14 plies to find the result. You are right and it is also clear from the main line that it can see the queen on the board and does not solve it for wrong positional reasons that vincent suggests. Uri
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