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Subject: Re: If you like to solve a mate...

Author: Heiner Marxen

Date: 16:03:55 02/04/01

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On February 04, 2001 at 12:33:53, Uri Blass wrote:

>On February 04, 2001 at 09:13:28, leonid wrote:
>
>>Hi!
>>
>>If you like to solve one forced mate...
>>
>>[D]6R1/r3P1b1/6kN/1bP1P1np/3P1B1p/4P3/pq4N1/r1n3QK w - -
>>
>>Please indicate you result.
>>
>>Thanks,
>>Leonid.
>
>I changed the side to move because white to move is too easy.
>
>Chessmaster6000 finds a mate in 8 in 36 seconds(it can also find a longer mate
>in less time.
>
>The solution begins with 1...Ne2 2.Nxh4+ Kh7 3.Rxg7+ Kxg7 4.e8N+ Kf8 5.Kh2 Rxg1
>
>Uri

... and continues: Nxg1  a1=Q   Bh2  Qxg1+  Bxg1 Ng3#

Chest gives the following PV:
Ne2 Nxh4+ Kh7 Kh2 Nxg1+ Ng2 N1f3+ Kg3 Ne4+ Kxf3 Rf1+ Kxe4 Qxg2+ Kf5 Qg6#

confirming that it is a mate in 8.  21.5 secs, K7/600 60MB hash.
The complete solution tree of Chest (without duals) is nearly 1700 lines.

The original problem was also easier for Chest.
Here its complete solution tree (with all duals):

1.         2.         3.         4.         5.        6.         7.        8.
Nxh4+ Kh7  Rxg7+ Kh8  Nf7+  Kxg7 Qxg5+ Kxf7 Qf6+ Ke8  Qf8+  Kd7  e8=Q+ Kc7 Qc8#
                                                 Kg8  Qf8+  Kh7  Qf7+  Kh8 Ng6#
                                            e6+  Kxe6 e8=Q+ Bxe8 Qf5+  Ke7 Bg5#
                                                            Re7  Qe5#
                                                                 Qexe7#
                                                                 Qf5#
                                                                 d5#
                                                 Ke8  Qg8+  Kxe7 Bg5#
                                       Kh7  Qg6#
                            Nxf7 Rg8+  Kh7  Qg6#
                                            Qg7#
                 Kxg7 Qxg5+ =*=  Qg8#
                 Kxh6 Nf5#
                      Qxg5#
      Kxh6 Qxg5+ Kh7  Qxg7#

That is quite a forcing line.  12.2 secs K7/600 60 MB hash.

Maybe we should retry all of Leonid's problems with side to move switched?
;-)

Heiner



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