Author: Uri Blass
Date: 21:16:07 02/12/01
Go up one level in this thread
On February 12, 2001 at 18:40:38, Heiner Marxen wrote: >On February 12, 2001 at 15:47:55, leonid wrote: > >>On February 12, 2001 at 13:11:53, Heiner Marxen wrote: >> >>>On February 12, 2001 at 07:29:02, leonid wrote: >>> >>>>Hi! >>>> >>>>If you like to solve a mate, try this position: >>>> >>>>[D]rQ1Q1rnk/q4qbp/3nQqbB/q1Q1NnNn/5QQ1/b2Q4/1QB3Q1/1K1R3R w - - >>>> >>>>Please, indicate your result. >>>> >>>>In dispite that this position is not that deep and difficult, if your program >>>>don't know how to deel with white crowd it could be in serious trouble. My was >>>>deadly slow in searching for mate even by selective search. Reason - white have >>>>142 initial moves and goes beyond 150 during the search for mate. Good challenge >>>>for every chess program! >>>> >>>>Thanks for responding, >>>>Leonid. >>> >>>Hmmm, not deep? Not difficult? "There is no mate in 6" by Chest burns >>>nearly 18 minutes on a K6-3/400 with 50MB hash. I have started depth=7, >>>but I expect at least 3 hours to complete it, and may be more. >>>At least I can confirm the 142 initial legal moves. >>> >>>Heiner >> >>Thanks, Heiner! You are very close! Mine found mate in 8 by selective. It was >>long. Took 1 min 17 sec. >> >>It is simple since there are not that many moves before the mate and starting >>move (for 8 moves) is checking one. >> >>Leonid. > >Phew, that was hard work: after 5.3 hours (K6-3/400, 50MB hash) Chest finds >a unique key for a mate in 7. Here is a PV: > >Ngxf7+ Nxf7 Nxg6+ hxg6 Bxg7+ Nfxg7 Qgxh5+ Nxh5 Qfxf6+ Ngxf6 Qdxf8+ Kh7 Qgxg6# > >What about the playing programs? Normally they are much faster to _find_ >a mate. Did nobody try it, or is this one also hard for them? > >Heiner My Junior5.9 found mate in 8 in a short time. Main line 1.Ngxf7+ Qaxf7 2.Bxg7+ Nfxg7(or 2...Q7xg7 3.Nxg6+ hxg6 4.Qxh5+ gxh5 5.Rxh5+ Qfh6 6.Rxh6+ Ngxh6 7.Qxf8+ Kh7 8.Qfxg7#) 3.Qfxf6 Rxb8 4.Nfxf7+ Nxf7 5.Qxg7+ Nxg7 6.Rxh7+ Kxh7 7.Qexg6 Kh8 8.Qh7# The part begins with 2...Q7xg7 is the main line of Junior after I give it only the position after 1.Ngxf7+ Qaxf7 I guess that it may be possible to learn from Junior's mistakes in this line about the rules of the selective search that Junior is using. Junior stops to search after finising an iteration when it finds a mate for itself so I need to give it a position with black to move if I want it to find a shorter mate. Time of Junior on p200MMX 1:40 19496 knodes were searched. Uri
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