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Subject: Re: One mate to solve for Champions!

Author: Paul

Date: 12:43:57 10/03/01

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On October 03, 2001 at 11:53:39, Heiner Marxen wrote:

>On October 02, 2001 at 09:52:50, Paul wrote:
>
>>On October 02, 2001 at 08:41:20, leonid wrote:
>>
>>>[D]kq4BK/pq4QQ/2qq1P2/1NnqBnN1/3PpP2/2P2r2/RQ4qr/RQ4bb w - -
>>>
>>>I have said that this position is for "Champions" only having in mind that some
>>>people will try to solve it by brute force. Brute force is the only way to know
>>>minimal nomber of moves that lead to mate. But it could be not all the time
>>>easy. When I tried this position on two professional program, I was impressed.
>>>On Celeron 600Mhz, and with 1M of hash, one expected to solve position in around
>>>4000 years. Other, with no hash, after around 11000000000 years of thinking
>>>expected to recognize shortest mate.
>>>
>>>Please indicate your result.
>>>
>>>Thanks,
>>>Leonid.
>>
>>Hi Leonid,
>>
>>I just now started to look at both your positions, the simple one from yesterday
>>and this one, and I think you have a bit of a twisted nomenclature!
>>
>>This one is the simple one, the other one is more difficult. Even if this one
>>seems to be a mate in 12, and the other in 9. But maybe that's only the case for
>>Pretz, I'm curious about LLchess.
>>
>>For this one I find a mate in 12 in 3 seconds by applying some gentle force:
>>
>>00:03 WM12 12 Rxa7+ Q8xa7 Rxa7+ Kb8 Rxb7+ Nxb7 Qf8+ Qc8 Qxc8+ Kxc8 Nxd6+ Nfxd6
>>Be6+ Kd8 Qb6+ Ke8 Bd7+ Kf8 Bxd6+ Nxd6 Qb8+ Nc8 Qxc8#
>
>Hi Leonid, Hi Paul!
>
>Since 1BELCT has finished, and my PC is reassembled, its time for a mate... :-)

Heiner, read you had a crash, sorry 'bout that ... but, I'd be happy to send you
all of Leonid's previous problems, so you can run them again ... ;0

>Chest confirms the above: Rxa7+ is the only key move for the shortest
>solution. It gives nearly the same PV:
>
>PV: Rxa7+ Q8xa7 Rxa7+ Kb8 Rxb7+ Nxb7 Qf8+ Qc8 Qxc8+ Kxc8 Nxd6+ Nfxd6 Be6+ Kd8
>Qb6+ Ke8 Bd7+ Kf8 Bxd6+ Qxd6 Qxd6+ Nxd6 Ne6#
>
>(9.5 minutes on a K7/600 with 350 MB hash).
>
>Heiner

Just for comparison: with the command 'chest319 -Z12 -b x.epd' in a DOS box
under Windows XP it took about 5'45" on my p3/1000. That's a linear speedup,
although I used probably only ~40MB hash (that's default, don't know how to set
hash in Chest, any tips?).

Paul



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