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Subject: Re: One very easy mate to solve.

Author: Heiner Marxen

Date: 22:43:20 05/22/01

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On May 22, 2001 at 00:43:13, Pete Galati wrote:

>On May 21, 2001 at 21:17:24, leonid wrote:
>
>>Hello!
>>
>>I was not sure what position to chose between three close mate positions.
>>Decided to put the simplest one today and hardest one at the end, later.
>>
>>[D]RqqkqqR1/rBNbNBr1/QnqRqnQ1/bqBRBqb1/Q2K2Q1/8/8/8 w - -
>>
>>Please indicate your result.
>>
>>Thanks,
>>Leonid.
>
>I needed to load Junior6 on this computer cause I plan to use it in the near
>future for an interface to run Comet in the 60 minute per move against Mogens'
>Gandalf, so this is what Junior6 had to say:
>
>New position
>RqqkqqR1/rBNbNBr1/QnqRqnQ1/bqBRBqb1/Q2K2Q1/8/8/8 w - - 0 1
>
>Analysis by Junior 6.0:
>
>1.Q4xb5 Qf2+ 2.Kd3 Qd2#
>  -+  (-#3)   depth: 3   00:00:00  6kN
>1.Qc2 Qxg4+ 2.Bf4 Qg1+ 3.Qf2 Qxf2+ 4.Be3 Bxe3#
>  -+  (-45.84)   depth: 3   00:00:00  19kN
>1.Rxd7+ Nbxd7 2.Nxc6+ Qexc6 3.Bxf6+ Bxf6+ 4.Nxb5
>  -+  (-10.25)   depth: 3   00:00:00  91kN
>1.Nxe6+ Qxe6 2.Nxc6+ Qbxc6 3.Rxd7+ Nbxd7 4.Bxb8
>  -+  (-7.44)   depth: 3   00:00:00  99kN
>1.Nxe6+!
>  -+  (-7.14)   depth: 6   00:00:00  210kN
>1.Nxe6+ Qxe6 2.Nxc6+ Qbxc6 3.Rxd7+ Qe6xd7 4.Qxd7+ Nfxd7 5.Qgxc6 Rxa6 6.Bxc8
>  -+  (-5.65)   depth: 6   00:00:00  316kN
>1.Nxe6+!
>  -+  (-5.35)   depth: 9   00:00:01  1336kN
>1.Nxe6+! Qxe6 2.Nxc6+ Qbxc6 3.Rxd7+ Qe6xd7 4.Qxf6+ Bxf6 5.Qxd7+ Qc8xd7 6.Rxb8+
>Qcc8 7.Qxd7+ Nxd7 8.Rxc8#
>  +-  (#8)   depth: 9   00:00:04  3868kN
>1.Nxe6+ Qxe6 2.Nxc6+ Qbxc6 3.Rxd7+ Qe6xd7 4.Qxf6+ Bxf6 5.Qxd7+ Qc8xd7 6.Rxb8+
>Qcc8 7.Qxd7+ Nxd7 8.Rxc8#
>  +-  (#8)   depth: 9   00:00:04  4113kN
>
>It came up with that really fast and then just stopped searching.  63mb hash,
>the computer's 700mhz Celeron.
>
>Pete

Well, yes, 4 seconds is about right :-)
Chest on a K7/600 (with >= 1MB hash) needs 1.43 sec to solve the mate in 8
and come up with these two PVs:

Nxc6+ Qxc6 Nxe6+ Qfxe6 Rxd7+ Qc6xd7 Qxf6+  Bxf6  Qxb6+  Bxb6   Qxd7+  Q6xd7
Qxd7+  Qcxd7 Rxb8#

Nxe6+ Qxe6 Nxc6+ Qbxc6 Rxd7+ Qc6xd7 Qxf6+  Bxf6  Qxb6+  Bxb6   Qxd7+  Q6xd7
Qxd7+  Qcxd7 Rxb8#

This is sort of an anti-Leonid  ;-)  The effective branching factor is
extremely small:

depth  seconds
#  3      0.01  0.93         62-         0
#  4      0.04  1.06        269-         0
#  5      0.16  1.34        839-         0
#  6      0.38  2.32       2021-         0
#  7      0.89  5.54       4776-         0
#  8      1.40  4.96       7774-         0

Hey, Leonid, what about some problems with lots of pawns?
That sort of piece is missing in your creations, up to now, right?

Cheers,
Heiner



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