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Subject: Re: One mate to solve...

Author: leonid

Date: 04:51:57 04/29/01

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On April 29, 2001 at 00:56:45, Heiner Marxen wrote:

>On April 27, 2001 at 21:58:22, leonid wrote:
>
>>On April 27, 2001 at 19:28:41, leonid wrote:
>>
>>>On April 27, 2001 at 18:44:32, Mike S. wrote:
>>>
>>>>On April 27, 2001 at 08:28:44, leonid wrote:
>>>>
>>>>>(...)
>>>>>[D]4nqqQ/1r2qR1Q/2q1NBQN/q3n1PK/kr1qn1RQ/4RBq1/5NpN/3bb2R b - -
>>>>
>>>>Black has the move?
>>>
>>>Yes.
>>>
>>>>Please tell at least how many moves the mate takes, to allow an estimation of
>>>>the calculation time required.
>>>
>>>I really don't know exact minimum amount of moves for this position and expect
>>>that somebody will come with response. I had too bad branching factor when I
>>>tried to solve it in perfect way. As a result, I saw this position by brute
>>>force only 6 moves deep (already 23 min). In 6 moves for sure no mate. And in 10
>>>- mate was found by my selective search. Shortest mate exist without any doubt
>>>between 7 and 10 moves.
>
>Chest on a K7/600 with 350 MB hash does not find a mate in 8 in nearly 3 hours.
>Since the effective branching factor is around 20, I give up, here.

You have good branching factor here. Mine had (no hash) 36 between 4 and 5 moves
and as much as 58 between 5 and 6 moves. Search done by brute force.

4 moves - 1 sec.
5 moves - 35 sec.
6 moves - 33 min. 58 sec.

By curiosity I looked into Genius 2 work. It was:

3 moves - 0 sec
4 moves - 33 sec.
5 moves - 39 min 45 sec.

It could be that it use small hash.

Cheers,
Leonid.

>For the "no mate in 6" Chest used only 34 seconds.
>
>Cheers, Heiner
>
>
>>Will just add, maybe this could help, that mate that my solver found started
>>with move g3-h4.
>>
>>
>>>Cheers,
>>>Leonid.
>>>
>>>>With white to move, I didn't find a #5, using Mate 2.0 with standard options.
>>>>
>>>>Regards,
>>>>M.Scheidl



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