Author: Uri Blass
Date: 06:46:50 10/02/03
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On October 02, 2003 at 08:49:10, Joachim Rang wrote: >Recently Pierre posted a very beautiful position, in which white can win in an >obviously lost position. > >http://talkchess.com/forums/1/message.html?318847 > >All engines need either very much time to solve this or can't solve it at all. >There are a few exceptions of programs, which do not consider underpromotions, >since black can prolong being mated by underpromotions. So Tao, Amateur and >Aristarch see a mate where there actually is no mate (yet). > >But SmarThink 0.17a can solve this in a few seconds on depth 8 even with the >right evaluation! Older versions of SmarThink can't solve this, so I think it's >due to the new "same thread extensions" which described Sergei here: > >http://talkchess.com/forums/1/message.html?318833 I do not understand how it can be 8 plies with the special extension Can you give me the remaining depth in the main line when you start at depth 8? 1.Nc6+ Kb7 2.Na5+ Kb6 3.Bf2+ Kxa5 4.e8Q Nc7+ 5.Kd6 Nxe8 6.Kc5 d2 7.Bd4 d1N 8.Be5 f2 9.Bf4 f1N 10.Bg5 Nf6 11.Bxf6 Nf7 12.Bh4 Nf2 13.Bxf2 Nd2 14.Be1 Be2 15.Bxd2# There are 29 plies for the mate. last ply may be thanks to qsearch. 6 moves are checks and are extended by 1 ply but there are still 22 plies. Even if you assume that every move that is not check is extended by 1/2 ply it is not enough to get it with less than 11 plies. The only way to solve it in 8 plies is if you have some repeat threat mate extension of 1 ply and not 1/2 ply and even in that case I do not see a reason to extend most of the moves of black so I do not understand the 8 plies. Uri
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