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Subject: Re: an easy (?) mate in 11

Author: Heiner Marxen

Date: 06:50:06 12/11/02

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On December 11, 2002 at 00:29:27, Mike S. wrote:

>In this study, Black has either only one legal move (1st-7th), or there is only
>one move which avoids immediate mate (8th/9th):
>
>Kok,T - [+3350.47g2b7]
>td06 {v}, 1938
>[D]qrb5/pk1p4/p2Pp3/p3Pp2/B4P2/1P6/5pK1/6B1 w - - 0 1
>1.Kxf2 Kb6 2.Ke2+ Kb7 3.Ke3 Kb6 4.Kd3+ Kb7 5.Kd4 Kb6 6.Kc4+ Kb7 7.b4 axb4 8.Bd1
>a5 9.Kb5 a6+ 10.Ka4 Qa7 11.Bf3# 1-0
>
>P3/700 MHz, 64 MB hash:
>
>Analysis by Goliath Light 1.5:
>
>1.Bxf2
>  -+  (-15.60)   Depth: 6/8   00:00:00
>  -+  (-15.64)   Depth: 7/9   00:00:00
>1.Kxf2 Kb6 2.Ke2+ Kb7 3.Ke3
>  =  (0.00)   Depth: 7/10   00:00:00  1kN
>  +-  (#11)   Depth: 16/39   00:00:10  14218kN
>
>
>Analysis by Nimzo 8:
>
>1.b4
>  -+  (-21.08)   Depth: 1/11   00:00:00
>1.Bc6+ Kxc6
>  -+  (-20.62)   Depth: 1/11   00:00:00
>  -+  (-20.12)   Depth: 1/11   00:00:00
>1.Bh2
>  -+  (-17.59)   Depth: 1/11   00:00:00
>  -+  (-17.59)   Depth: 1/11   00:00:00
>1.Bxf2
>  -+  (-14.96)   Depth: 1/11   00:00:00
>  =  (0.00)   Depth: 16/34   00:00:03  991kN
>1.Kxf2 Kb6 2.Ke2+ Kb7 3.Ke3 Kb6 4.Kd3+ Kb7 5.Kd4 Kb6 6.Kc4+
>  +-  (#5)   Depth: 16/34   00:00:03  991kN
>  +-  (#9)   Depth: 16/34   00:00:08  4346kN
>
>(Too small number of moves in the mate announcement is typical for N8, but the
>pv is ok so far.)
>
>
>Analysis by Yace 0.99.56:
>
>1.Bxf2
>  -+  (-11.79)   Depth: 1   00:00:00
>  =  (0.00)   Depth: 16/28   00:00:04  2339kN
>1.Kxf2 Kb6 2.Ke2+ Kb7 3.Ke3 Kb6 4.Kd3+ Kb7 5.Kd4 Kb6 6.Kc4+ Kb7 7.b4 axb4 8.Kxb4
>a5+ 9.Kxa5 a6 10.Bd1 Qa7 11.Bf3#
>  +-  (#11)   Depth: 16/28   00:00:05  2753kN
>  +-  (#11)   Depth: 18/28   00:00:22  15212kN
>
>Perfect.
>
>Regards,
>M.Scheidl

This one is easy even for Chest:  on an Athlon 1500+ Chest needs 20.68 seconds
to be sure about the solution, and 37.47 secs to print the complete solution
tree.  Chest confirms that this is a mate in 11 with a unique key move:

PV: Kxf2 Kb6 Ke2+ Kb7 Ke3 Kb6 Kd3+ Kb7 Kd4 Kb6 Kc4+ Kb7 b4 axb4 Bd1 a5 Kb5 a6+
Kxa5 b3 Bf3#

The complete solution tree is not much larger:

 Kxf2 Kb6 Ke2+ Kb7 Ke3 Kb6 Kd3+ Kb7 Kd4 Kb6 Kc3+ Kb7 b4 axb4+ Kxb4 a5+ Kxa5 a6
Bd1  =*= Bf3#
                                            Kc4+ Kb7 b4 axb4  Bd1  a5  Kb5  a6+
Ka4  =*= Bf3#

Kc4  =*= Bf3#

Kxa5 =*= Bf3#
                                                                            -*-
Bf3#
                                                                   -*- Bf3#
                                                              Kxb4 a5+ Kxa5 a6
Bd1  =*= Bf3#

Cheers,
Heiner



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