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Subject: Re: One mate to solve for fittest programs.(done)

Author: Angrim

Date: 22:48:34 05/04/01

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On May 04, 2001 at 16:05:36, leonid wrote:

>On May 04, 2001 at 15:38:23, Angrim wrote:
>
>>On May 04, 2001 at 10:26:02, leonid wrote:
>>
>>>Hello!
>>>
>>>Had bad lack this midnight when one call came from my work. It took me 20
>>>minutes to do it but I went to my bed only at 2 o'clock. One good result from
>>>broken sleep was this position that you can try to solve. It probably will
>>>demand one sleepless night from your program, if you will insist on shortest
>>>mate.
>>>
>>>[D]RnqkqnR1/qBNbNBq1/QqQqQqQ1/BrQqQrB1/3q4/8/3Q4/3K4 w- -
>>>
>>>Please indicate your result.
>>>
>>>Thanks,
>>>Leonid.
>>
>>this one IS tough, wonder if having endgame tables would help a lot?
>
>Never!
ok, it just looked like there were some lines where most of the pieces
would get swapped off.

>
>>I'll leave my proof number searcher running while I'm at work, maybe it
>>will find an answer in a few hours.. currently its obsessing over Qxd7.
>
>Everything depend on each program branching factor. Two professional that I
>tried until now (they are not specialized in solving mate nut never hung on you)
>were slow. The every next program could have very good branching factor for this
>position. I had the chance to see very good on mine, mainly for brute  force.
>Selective was slow. It took this in 10 min 42 sec. Celeron 600Mhz. No hash.
>
>Leonid.
>

program finished shortly after I left for work
proved that move e6xd7 wins, 17 turns
PN2:94098802 evals, 2821179 expands 1258.90 seconds

I am sure that it did not find the shortest mate, since pn search is
incredibly selective.  It searched most lines to 12 ply, but a few went
as deep as 73 ply(these may have traded down to K vs Kb or some such).

It ended up proving that 44 of the 69 legal moves for white lost.
Angrim



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