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Subject: Re: One very easy mate to solve.

Author: leonid

Date: 19:45:11 05/23/01

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On May 23, 2001 at 19:35:00, Heiner Marxen wrote:

>On May 23, 2001 at 15:37:07, leonid wrote:
>
>>
>>>Hey, Leonid, what about some problems with lots of pawns?
>>>That sort of piece is missing in your creations, up to now, right?
>>
>>Hi, Heiner!
>>
>>I don't use that much pawns since they signify little mobily. This last position
>>came just from three close positions that had pawns. If I presented before
>>without pawns it is because it was the simplest one. Very few people here are
>>ready for some deep thinking before week-end. Now you can see the other two,
>>even if initially I expected to write only deepest mate. Anyway, both positions
>>are very easy and accessible for every possible program. They have limited
>>number of moves to start. Everybody can try and solve them.
>>
>>[D]RqqkqqR1/rPNbNPr1/QnqBqnQ1/bqRQRqb1/Q2K2Q1/3B4/8/8 w - -
>
>This one is quite easy even for Chest's brute force attack: K7/600, 47.74 sec.
>Six key moves lead to mate in 9:

Pretty good time!

Mine found only after 13 min that mate not exist in 8 moves. Mate in 9 (first
mate) was found in 1 min and 23 sec. Selective do good work here. It find mate
in 9 moves in 3 sec.


>
>Nxc6+  Qxc6 fxe8Q+ Nxe8  bxc8Q+ Qxc8  Nxe6+  Qxe6  Q4xg5+ Qee7  Bxe7+  Qxe7
>Rxe8+  Kc7  Rxc6+  Bxc6  Qgxc6#
>
>Nxe6+  Qxe6 fxe8Q+ Nxe8  Nxc6+  Qbxc6 Q4xg5+ Re7   Bxe7+  Qfxe7 bxc8Q+ Nxc8
>Qxe8+  Kc7  Qd8+   Qxd8  Qxd8#
>
>bxc8Q+ Nxc8 fxe8Q+ Qxe8  Nxc6+  Qxc6  Nxe6+  Qxe6  Q4xa5+ Qbc7  Be7+   Kxe7
>Rxe6+  Bxe6 Qgxe6+ Qxe6  Qaxe6#
>
>bxc8R+ Nxc8 fxe8Q+ Qxe8  Nxc6+  Qxc6  Nxe6+  Qxe6  Q4xa5+ Qbc7  Be7+   Kxe7
>Rxe6+  Bxe6 Qgxe6+ Qxe6  Qaxe6#
>
>fxe8Q+ Nxe8 bxc8Q+ Qxc8  Nxc6+  Qxc6  Nxe6+  Qxe6  Q4xg5+ Qee7  Bxe7+  Qxe7
>Rxe8+  Kc7  Rxc6+  Bxc6  Qgxc6#
>
>fxe8R+ Nxe8 bxc8Q+ Qxc8  Nxc6+  Qxc6  Nxe6+  Qxe6  Q4xg5+ Qee7  Bxe7+  Qxe7
>Rxe8+  Kc7  Rxc6+  Bxc6  Qgxc6#
>
>>[D]RrqkqrR1/qPNbNPq1/BnqBqnB1/bqQQQqb1/Q2K2Q1/3B4/8/8 w - -
>
>This one has an even smaller effective branching factor.  It has the same
>set of solution moves, but it is a mate in 12:

Here I was not sure where is the mate. Your finding is useful. 10 moves took
already 6 hours and 28 minutes to say that no mate exist. For 11 moves it could
be expected as 50 hours. Branching factor started to grow for my program just
after 7 moves. It was between 4 and 5 move - 5.4. Mate was found for sure in 13
moves by selective. Took 7 sec. Big number of possible solutions make this
position quit useful for possible logic verification.

Cheers,
Leonid.

>Nxc6+  Qxc6 bxc8Q+ Rxc8 Nxe6+  Qfxe6 fxe8Q+ Rxe8 Rxe8+  Nxe8  Qxg5+  Nf6   Rxc8+
> Nxc8  Qxa5+  Nb6   Qexe6  Qa4+  Qxa4   Bc6   Be7+   Kc7   Qge5#
>
>Nxe6+  Qxe6 fxe8Q+ Rxe8 Nxc6+  Qbxc6 bxc8Q+ Rxc8 Rxe8+  Nxe8  Qxg5+  Nf6   Rxc8+
> Nxc8  Qxa5+  Nb6   Qexe6  Qa4+  Qxa4   Bc6   Be7+   Kc7   Qge5#
>
>bxc8Q+ Rxc8 fxe8Q+ Rxe8 Nxc6+  Qxc6  Nxe6+  Qxe6 Rxe8+  Nxe8  Qxg5+  Nf6   Rxc8+
> Nxc8  Qxa5+  Nb6   Qexe6  Qa4+  Qxa4   Bc6   Be7+   Kc7   Qge5#
>
>bxc8R+ Rxc8 fxe8Q+ Rxe8 Nxc6+  Qxc6  Nxe6+  Qxe6 Rxe8+  Nxe8  Qxg5+  Nf6   Rxc8+
> Nxc8  Qxa5+  Nb6   Qexe6  Qa4+  Qxa4   Bc6   Be7+   Kc7   Qge5#
>
>fxe8Q+ Rxe8 bxc8Q+ Rxc8 Nxc6+  Qxc6  Nxe6+  Qxe6 Rxe8+  Nxe8  Qxg5+  Nf6   Rxc8+
> Nxc8  Qxa5+  Nb6   Qexe6  Qa4+  Qxa4   Bc6   Be7+   Kc7   Qge5#
>
>fxe8R+ Rxe8 bxc8Q+ Rxc8 Nxc6+  Qxc6  Nxe6+  Qxe6 Rxe8+  Nxe8  Qxg5+  Nf6   Rxc8+
> Nxc8  Qxa5+  Nb6   Qexe6  Qa4+  Qxa4   Bc6   Be7+   Kc7   Qge5#
>
>Although only 40MB hash have been used, it helped a lot (factor 13).
>K7/600, 163.78 sec.
>
>Cheers,
>Heiner



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