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Subject: Re: Test - a-pawn and wrong bishop

Author: Ernst Walet

Date: 11:34:23 02/27/01

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On February 27, 2001 at 12:18:53, Sune Larsson wrote:

>
>  [D]8/8/pp6/3b2K1/1P6/PN2k3/8/8 w - - 0 1
>
>
>  This is old swedish chess history. The above position happened in a game
>  between Bergkvist and Stolz, Stockholm 1941. White is in deep trouble.
>  Knight moves to a1 or c2 will just lose the lonely one. But the knight
>  has a more brave possibility! 1.Na5!! actually saved the draw for white.
>  After 1.-bxa5 2.bxa5 black has the wrong bishop and white's king can just
>  make it to a1, if black goes for both the white a-pawns.
>
>  The game went like this: 1.Na5!! Kd3 2.Kf6 Kc3 3.Ke5 Bg2 4.Kd6 b5 5.Kc5 Kb2
>  6.Kb6 Kxa3 7.Kxa6 ½-½
>
>  Test: This is a difficult one for chess programs and presupposes
>        extended knowledge about a/h pawn and the wrong bishop.
>
>  Sune


Hi Sune, Fritz6 plays Na5 in one minute one second on my P3-500 with 128MB hash
and 3+4 EGTB, but a draw score is out of reach.

Ernst.

New position
8/8/pp6/3b2K1/1P6/PN2k3/8/8 w - - 0 1

Analysis by Fritz 6:

1.Nc5 bxc5 2.bxc5
  -+  (-1.72)   Depth: 1/4   00:00:00
1.Nc5 bxc5 2.bxc5
  -+  (-1.72)   Depth: 1/4   00:00:00
1.Nc1!
  µ  (-0.87)   Depth: 1/4   00:00:00
1.Nc1!
  ³  (-0.37)   Depth: 1/4   00:00:00
1.Nc1 Ke4
  ³  (-0.37)   Depth: 2/3   00:00:00
1.Nc1--
  ³  (-0.69)   Depth: 3/6   00:00:00
1.Nc1-- Kd2 2.b5 Kxc1 3.bxa6
  -+  (-1.59)   Depth: 3/7   00:00:00
1.Na1!
  -+  (-1.41)   Depth: 3/7   00:00:00
1.Na1! Ke4 2.Nc2
  ³  (-0.34)   Depth: 3/7   00:00:00
1.Na1 Ke4 2.Nc2 Bc6
  ³  (-0.31)   Depth: 4/8   00:00:00
1.Na1 Ke4 2.Nc2 Bb3 3.Ne1
  ³  (-0.34)   Depth: 5/10   00:00:00  1kN
1.Na1 Ke4 2.Nc2 Kd3
  ³  (-0.37)   Depth: 6/10   00:00:00  2kN
1.Na1 Ke4 2.Nc2 Kd3 3.Na1 Kd4
  ³  (-0.37)   Depth: 7/10   00:00:00  4kN
1.Na1 Ke4 2.Nc2 Kd3 3.Na1 Bf7 4.Kf5 Bc4
  ³  (-0.31)   Depth: 8/12   00:00:00  9kN
1.Na1 Ke4 2.Nc2 Bc6 3.Ne1 Bb7 4.Kf6 Bc6 5.Ng2
  ³  (-0.34)   Depth: 9/16   00:00:00  20kN
1.Na1 Ke4 2.Nc2 Bc6 3.Ne1 Bb7 4.Kf6 Kd4 5.Ke6 Bd5+
  ³  (-0.31)   Depth: 10/15   00:00:00  38kN
1.Na1--
  ³  (-0.62)   Depth: 11/18   00:00:00  90kN
1.Na1-- Kd3 2.Kf6 Kc3 3.Ke5 Ba8 4.b5 Kb2 5.bxa6 Kxa1
  µ  (-0.97)   Depth: 11/18   00:00:00  118kN
1.Na1 Kd3 2.Kf6 Kc3 3.Ke5 Ba8 4.Kd6 Kb2 5.Kc7 b5
  µ  (-0.97)   Depth: 12/19   00:00:00  196kN
1.Na1--
  µ  (-1.28)   Depth: 13/20   00:00:00  265kN
1.Na1-- Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.Kd6 Kb2 5.Kc7 b5
  -+  (-2.37)   Depth: 13/20   00:00:01  390kN, tb=1
1.Na1 Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.Kd6 Kb2 5.Kc7 b5
  -+  (-2.44)   Depth: 14/23   00:00:02  690kN, tb=3
1.Na1--
  -+  (-2.75)   Depth: 15/20   00:00:02  871kN, tb=8
1.Na1-- Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.a4 Kb2 5.a5 bxa5
  -+  (-2.81)   Depth: 15/21   00:00:03  1127kN, tb=11
1.Na1 Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.a4 Kb2 5.a5 b5
  -+  (-2.91)   Depth: 16/22   00:00:04  1777kN, tb=44
1.Na1 Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.a4 Kb2 5.a5 b5
  -+  (-2.97)   Depth: 17/23   00:00:08  3139kN, tb=209
1.Na1 Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.a4 Kb2 5.a5 b5
  -+  (-2.97)   Depth: 18/25   00:00:13  5157kN, tb=508
1.Na1 Kd3 2.Kf6 Kc3 3.Ke5 Bc4 4.a4 Kb2 5.a5 b5
  -+  (-2.97)   Depth: 19/29   00:00:29  11515kN, tb=1755
1.Na1--
  -+  (-3.28)   Depth: 20/29   00:00:51  20487kN, tb=5365
1.Na1--
  -+  (-3.28)   Depth: 20/29   00:00:54  21882kN, tb=5468
1.Na5!
  -+  (-3.25)   Depth: 20/29   00:01:01  24801kN, tb=6504
1.Na5! bxa5 2.bxa5 Bc4 3.Kf6 Kd4 4.Ke7 Ke5 5.Kf8 Bb3
  -+  (-3.03)   Depth: 20/29   00:01:08  28171kN, tb=7079
1.Na5 bxa5 2.bxa5 Bc4 3.Kf6 Kd4 4.Kf5 Ba2 5.Kf4 Bb1
  -+  (-3.03)   Depth: 21/29   00:01:56  48588kN, tb=15301
1.Na5 bxa5 2.bxa5 Bc4 3.Kf6 Kd4 4.Kf5 Ba2 5.Kf4 Bb1
  -+  (-3.03)   Depth: 22/29   00:02:55  73275kN, tb=23861
1.Na5 bxa5 2.bxa5 Bc4 3.Kf6 Kd4 4.Kf5 Ba2 5.Kf4 Bb1
  -+  (-3.03)   Depth: 23/30   00:05:15  131333kN, tb=46406



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