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Subject: Re: If you like to solve a mate...

Author: leonid

Date: 16:55:47 02/12/01

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On February 12, 2001 at 18:50:51, Dann Corbit wrote:

>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?
>
>I got tired of them because you can see at a glance that they will never occur
>in a game.  Far more interesting to me is the solution of practical mates.

What you are saying have a real sense. Only what are the real positions from
real game? Mates between 3 and 5 moves. Very seldom up to 7 moves. When those
mate in 7 ever happened, they were probably never annouced in advance, like
computers do. Was human player actually aware of them? But position of programs
is very clear. They solve instantly 3 or 5 moves mate, good for human. Those
rare human 7 moves mates they usually do in less that one second. Right now we
came to the point when chess program became just too smart for solving trivial
human mate.

Leonid.




>There seems to be one or two 10 queen type mate problems posted per day.  I
>doubt very much if a real chess engine running games will encounter a single
>such problem in a lifetime.



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