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Subject: Re: One very easy mate to solve.

Author: Heiner Marxen

Date: 16:35:00 05/23/01

Go up one level in this thread


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:

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:

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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