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Subject: Re: Why is this position so difficult?

Author: Roy Eassa

Date: 15:29:05 05/21/02

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On May 21, 2002 at 15:26:39, Andreas Herrmann wrote:

>On May 21, 2002 at 01:00:36, Jouni Uski wrote:
>
>>[D]1q1r3k/3P1pp1/ppBR1n1p/4Q2P/P4P2/8/5PK1/8 w - -
>>
>>None of my engines finds Rxf6 in reasonable time e.g. under 30 minutes! What's
>>so
>>special there, is it null-move problem may be? I guess Rebel can find it am I
>>right?
>>
>>Jouni
>
>Hi Jouni,
>
>i'm not sure what's the problem with other programs and i don't know if Rxf6 is
>the best move, but my engine Holmes (with not much chess knowledge implemented)
>found it in ply one under 1 centisecond on my slow K6/2 450.
>What moves want other programs here to play? Perhaps there is a better move.
>
>>1.1      -118        1        135 1.f2f3 [ 14kNs  0:00 n135]
>>1.7       -90        1        285 1.g2g1 [ 28kNs  0:00 n285]
>>1.35      -63        1        355 1.d6f6 [ 36kNs  0:00 n355]
>>2.35      -63        1        430 1.d6f6 [ ! 43kNs  0:00 n430]
>>2.1         2        1        492 1.d6f6 b8e5 [ 49kNs  0:00 n492]
>>3.1         2        1        671 1.d6f6 b8e5 2.f4e5 [ 67kNs  0:00 n671]
>>4.1        39        4       3629 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 [ 91kNs  0:00 n3629]
>>5.1        39        7       7371 1.d6f6 b8e5 2.f6h6 g7h6 [ 105kNs  0:00 n7371]
>>6.1        50       29      27743 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 d8g8 4.g2f3 h8g7 [ 96kNs  0:00 n27743]
>>7.1        43       62      58564 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 d8g8 4.g2f3 h8g7 5.f3e4 [ 94kNs  0:00 n58564]
>>8.1        55      162     168642 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 d8g8 4.g2f3 h8h7 5.f3e4 h7g7 [ 104kNs  0:01 n168642]
>>9.1       103      323     342310 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 d8g8 4.g2h1 h8h7 5.f2f4 h7g7 6.f4f5 [ 106kNs  0:03 n342310]
>>10.1       81      747     777524 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 d8g8 4.g2f1 h8g7 5.f2f4 a6a5 6.f4f5 g7h8 [ 104kNs  0:07 n777524]
>>11.1       85     2155    2348988 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 a6a5 4.f2f4 h8g7 5.g2f3 d8b8 6.f4f5 b8g8 [ 109kNs  0:21 n2348988]
>>12.1       93     5773    6100419 1.d6f6 b8e5 2.f6h6 g7h6 3.f4e5 d8g8 4.g2f3 h8g7 5.f3e4 a6a5 6.f2f4 g8b8 7.f4f5 b8g8 [ 106kNs  0:57 n6100419]
>
>have a nice day
>Andreas
>
>http://wbholmes.de


But the main line you show gives the wrong second move for White.  To win, White
should _avoid_ playing 2.Rxh6+ and instead recapture the Queen.

Here's a bit of analysis:

1.Rxf6!

   [1.Qd4 Qc7 2.Rxf6 gxf6 3.Qxf6+ Kg8 4.Qxh6 Rxd7 5.Qg5+ Kf8 6.Bxd7 Qxd7
    7.h6 Qd4 8.f5 Qe4+ 9.Kg3 Qe5+ 10.Kh3 Qd5 11.Qg7+ Ke8 12.Kg3 Qd3+
    and I don't know if White can win]

1...Qxe5 2.fxe5!

   [2.Rxh6+ gxh6 3.fxe5 Kg7 4.f4 Kf8 and I doubt White can win]

2...gxf6 3.exf6 and Black's King is locked out so White uses his King to win at
will.



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