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Subject: Re: Testposition - Good knight vs bad bishop III

Author: Sune Larsson

Date: 00:59:47 03/10/01

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On March 10, 2001 at 00:33:33, Robert Hyatt wrote:

>On March 09, 2001 at 08:08:01, Sune Larsson wrote:
>
>>
>>  [D]8/6b1/4k2p/p1p1p1p1/2P1K1P1/PP3N1P/8/8 w - - 0 1
>>
>>  Cortlever, 1940
>>
>>  Knight vs bishop and 5 pawns each. The black pawns are tied to squares
>>  of the same color as the bishop. This is the classic "bad bishop" and
>>  the position is won for white. But how to do it?  Putting the knight
>>  on f5 and then create Zugzwang for black with a4, doesn't seem enough
>>  for a win...
>>
>>
>>  Test: Can your program win this position, playing white?
>>        The solution, with lines by the author, further down.
>>
>>
>>  Sune
>>
>
>
>Crafty on my notebook says that Ne1 wins a pawn.  Takes just a second or two
>to find this.  After 2 minutes the eval is still over +1.  Looks like a zug
>with black having to push the e pawn and losing it.  Here is the last
>couple of search results:
>
>               14->   7.28   0.56   1. Ne1 Bf6 2. Nd3 Kd6 3. b4 cxb4 4.
>                                    axb4 axb4 5. Nxb4 Bg7 6. Nd5 Kc5 7.
>                                    Kd3 Bf8
>               15    10.39   0.47   1. Ne1 Bf6 2. Nd3 Kd6 3. Kf5 Bg7 4.
>                                    Nf2 Kd7 5. Ke4 Kc6 6. Nd3 Kd6 <HT>
>               15->  13.29   0.47   1. Ne1 Bf6 2. Nd3 Kd6 3. Kf5 Bg7 4.
>                                    Nf2 Kd7 5. Ke4 Kc6 6. Nd3 Kd6 <HT>
>               16    17.57     ++   1. Ne1!!
>               16->  32.09   0.86   1. Ne1 Bf6 2. Nd3 Kd6 3. Kf5 Bg7 4.
>                                    Nf2 Kd7 5. Ke4 Kc6 6. Nd3 Kd6 <HT>
>               17     1:03   1.00   1. Ne1 Bf8 2. Nd3 Bd6 3. a4 Kf6 4.
>                                    Kd5 e4 5. Kxe4 Ke6 6. Ne1 Bg3 7. Nc2
>                                    Bf2 8. Kf3 Bh4 9. Ke4
>               17->   1:25   1.00   1. Ne1 Bf8 2. Nd3 Bd6 3. a4 Kf6 4.
>                                    Kd5 e4 5. Kxe4 Ke6 6. Ne1 Bg3 7. Nc2
>                                    Bf2 8. Kf3 Bh4 9. Ke4
>               18     2:08   1.05   1. Ne1 Bf8 2. Nd3 Bd6 3. a4 Kf6 4.
>                                    Kd5 e4 5. Kxe4 Ke6 6. Ne1 Bg3 7. Nc2
>                                    Bf2 8. Ne3 Bxe3 9. Kxe3 Ke5
>               18->   2:59   1.05   1. Ne1 Bf8 2. Nd3 Bd6 3. a4 Kf6 4.
>                                    Kd5 e4 5. Kxe4 Ke6 6. Ne1 Bg3 7. Nc2
>                                    Bf2 8. Ne3 Bxe3 9. Kxe3 Ke5


  The above line 1.Ne1 Bf8 2.Nd3 Bd6 3.a4  and now 3.-Bf8 4.Nxe5 Bd6 is
  given as a draw by the author. See below.

  Sune
>
>
>
>
>>
>>
>>
>>
>>
>>
>>
>>
>>Cortlever,N
>>1940
>>
>>1.h4!
>>
>>[1.Ne1? Bf8 2.Nd3 Bd6 3.a4 Bf8 4.Nxe5 Bd6;
>>1.Nd2 Bf8 2.Nf1 Bd6 3.Ng3 Be7 4.Nf5 Bf8 5.a4 Bd6! 6.Nxd6 (6.Nxh6 Be7) 6...Kxd6
>>7.Kf5 e4 8.Kxe4 Ke6]
>>
>>1...gxh4 2.Nxh4 Bf8 3.Nf3 Bd6 4.Ne1 Kf6
>>
>>[4...Bf8 5.Nd3 Bd6 6.a4 Bf8 7.Nxe5 Bd6 8.Nd3 Bf8 (8...Be7 9.Nf4+ Kf6 10.Nd5+)
>>9.Nf4+ Kf6 10.Kd5 Kg5 11.Ne6+]
>>
>>5.Kd5 Bb8 6.Kxc5 Kg5 7.Kd5 Kxg4
>>
>>[7...Kf4 8.Nd3+ Kxg4 9.Nxe5+]
>>
>>8.Ke4 Bd6
>>
>>[8...h5 9.b4 axb4 10.axb4 h4 11.c5 Ba7 12.Nf3]
>>
>>9.Nc2 h5 10.b4 axb4 11.axb4 h4 12.Ne3+ Kg3 13.c5 1-0



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