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Subject: Re: Very easy mate to solve.

Author: leonid

Date: 15:13:00 05/05/01

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On May 05, 2001 at 17:47:38, Heiner Marxen wrote:

>On May 05, 2001 at 12:41:18, Paul wrote:
>
>>On May 05, 2001 at 11:55:58, leonid wrote:
>>
>>>Hello!
>>>
>>>If you would like to solve very easy mate, you can do this by solving one
>>>position from two, or both.
>>>
>>>[D]qk1r4/bpp1R1p1/pB1pnp2/N1Nb3p/2P1P3/QRnP2PB/5PK1/1r6 w - -
>>
>>Hi Leonid,
>>
>>this one is instantly solved by Pretz as a mate in 9:
>>
>>00:00 WM9 07 Nc6+ Bxc6 Nxa6+ bxa6 Bxc7+ Kc8 Qxa6+ Qb7 Bxe6+ Rd7 Bxd7+ Kxc7 Bxc6+
>>Kc8 Qxb7+ Kd8 Re8#
>
>As always, Pretz is faster than Chest.  As often, Pretz in fact finds the
>shortest possible mate.  I'm impressed, really!

I completely agree with you!

His program somehow did exactly like mine for both positions in number of moves
that lead to mate by selective search.

I solved two of them by selective and expected that you will come with minimum
moves to fix it for all of us. I could see that both have very bad branching
factor. I will come by curiosity to see how professional program do on these
positions. Recently, I could see that one program had better branching factor
that mine on one position that look like "natural". In reality, all my positions
is simple fantasy.

Cheers,
Leonid.

>1.Nc6+ is the only key for mate in 9.  Without duals this is a complete
>solution tree:
>
> Nc6+ Bxc6 Nxa6+ bxa6 Bxc7+ Kc8 Qxa6+ Qb7 Bxe6+ Rd7 Bxd7+ Kxc7 Bxc6+ Kc8 Bxb7+
>=*= Qxd6#
>                                                                     Kd8 Re8+
>Kc7 Qxb7#
>                                                                     Kb8 Qxb7#
>                                                          Bxd7 Qxb7#
>                                                Bd7 Qxb7#
>                                      Bb7 Bxe6+ Rd7 Bxd7+ Kxc7 Be6+  =*= Qxd6#
>                 Kc8  Rxc7#
>      bxc6 Bxc7+ Kc8  Qxa6+ Qb7 Qxb7#
>      Kc8  Rxc7#
>
>Took 48.1 minutes on K7/600 with 350 MB, so it wasn't exactly "easy" for Chest.
>
>>>[D]3k4/b2r4/4q3/2q3n1/1nnNbqnN/1Q1qpNBQ/r1BPQPp1/qNQRKR1N b - -
>>
>>And this one took a while longer as usual with your creations :), mate in 8:
>>
>>01:22 BM8 07 exf2+ Nxf2 Qaxd4 Bxd3 Qxf2+ Bxf2 Qxf2+ Rxf2 Bxf2+ Qxf2 Bxd3+ Qe3
>>g1=Q+ Nxg1 Qf2#
>>
>>Greetings,
>>Paul
>
>Oh yes, this one is harder.  Up to now I know that there is no mate in 6
>(471 secs), and the effective branching factor appears to be above 20.
>Therefore I estimate well over 2 days for the mate in 8 to complete.
>I think I will let him do it.  OTOH, within these two days Leonid will
>come up with at least two more of these  ;-)  Such is life.
>
>Groetjes,
>Heiner



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