Computer Chess Club Archives




Subject: Re: One mate to solve... that now is very easy.

Author: Heiner Marxen

Date: 10:26:26 05/06/01

Go up one level in this thread

On May 06, 2001 at 11:55:05, Paul wrote:

>On May 06, 2001 at 10:13:27, leonid wrote:
>>On May 06, 2001 at 06:22:26, leonid wrote:
>>>If you would like to solve a mate, you can try this moderate position:
>>>[D]Qqrkrq1Q/1QqqqqQ1/qBbnnbBq/1NQ2QN1/8/2Q2Q2/3RR3/3K4 w - -
>>>Please indicate your result.
>Ok ... my guess, before Heiner moves in with his heavy artillary, a mate in 9:
>06:18 WM9 09 Bxc7+ Qbxc7 Qxc7+ Qxc7 Qxd6+ Qcxd6 Nxe6+ Qexe6 Qfxf6+ Re7 Rxd6+
>Qxd6+ Qxd6+ Bd7 Qhxf8+ Qxf8 Qcc7#

Well, 6:18 is not exactly fast, right?
I will try this one later, have started with the second one.  See below.

>>After sending this last position I went to see its branching factor on one
>>professional program. I took it recently from the Web. After thinking for a
>>while program stopped breathing. Sudden death. Then I felt me a little bit
>>guilty by presenting upper position for Sunday. Better will be the next one that
>>is really. I did it yesterday before comming to the position that is above.
>No ... it wasn't too hard, Leonid! You must really be a nice guy, thinking about
>our feelings like that, thanks! ;)

The one who tortures us daily with bizarre mate problems?  :-))

But seriously: if they are too hard, he will not get much helpful response.
OTOH, we may feel pressed to improve our programs...

>>[D]nqrkrqn1/1QqnnqQ1/1BnbbnB1/BQNNNNQB/8/8/3RR3/3KQ3 w - -
>>Please indicate your result.
>This one's a bit too easy, haha, found a mate in 6:
>00:04 WM6 06 Qxc7+ Nxc7 Nxd6 Nxa5 Qxd7+ Nxd7 Nc6+ Nxc6 Ncb7+ Qxb7 Nxb7#

For sure it really is a mate in 6:
ChestMate = Pretzmate /* -1 */;		/* bugfix by Heiner */

It has multiple solutions, there are 6 key moves:

Bxc7+ Nxc7  Qxc7+  Bxc7  Bxf7   Bxd5  Nxc6+  Nxc6  Rxe8+  Qxe8  Qxe8#
Bxf7  Nxc5  Nxc6+  Nxc6  Q7xc6  Bd7   Rxe8+  Bxe8  Qexe8+ Qxe8  Qxe8#
Nxc7  Bb3+  Qxb3   Nxc7  Nxc6+  Nxc6  Qbxf7  Nce5  Qxd7+  Nxd7  Qxd7#
Nxd6  Naxb6 Q7xb6  Nxa5  Nexf7+ Bxf7  Nf4    Bb3+  Qxb3   Ne5   Ndb7#
Qxc7+ Nxc7  Bxc7+  Bxc7  Bxf7   Bxd5  Nxc6+  Nxc6  Rxe8+  Qxe8  Qxe8#
Qxf7  Qxf7  Nxf7+  Bxf7  Nxd6   Nde5  Nxf7+  Nxf7  Nxc7+  =*=   N7e6#

That took 28.4 minutes (!) (K7/600, 350MB hash)

depth  seconds
#  3      0.15  0.99        386-         0
#  4      4.19  1.25       9199-         0
#  5     95.47  1.55     219507-         0
#  6   1704.26  1.86    4219473-      9977

Chest needed an average of 2.5 black moves to refute at the top level,
what is unusually large, and contributes to the comparatively large time.

>Have a nice Sunday,

Thanks!  Dito!

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