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Subject: Rebel Century never sees Na5

Author: Arturo Ochoa

Date: 10:34:52 02/27/01

Go up one level in this thread


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

Thinking....

  +---+---+---+---+---+---+---+---+   -
8 |   |   |   |   |   |   |   |   |
  +---+---+---+---+---+---+---+---+  00:00:00      00:16:11
7 |   |   |   |   |   |   |   |   |
  +---+---+---+---+---+---+---+---+
6 | *p| *p|   |   |   |   |   |   |  Time          infinite
  +---+---+---+---+---+---+---+---+  Hash         200 Mb
5 |   |   |   | *B|   |   | K |   |  Engine        Rebel Century 3.0
  +---+---+---+---+---+---+---+---+  Personality   Rebel Century 3
4 |   | p |   |   |   |   |   |   |  anti-GM       Off
  +---+---+---+---+---+---+---+---+  Tactics       Off
3 | p | N |   |   | *K|   |   |   |  Bluff Chess   Off
  +---+---+---+---+---+---+---+---+  Style         Normal
2 |   |   |   |   |   |   |   |   |  Strength      Strongest
  +---+---+---+---+---+---+---+---+  Search        Normal Search
1 |   |   |   |   |   |   |   |   |
  +---+---+---+---+---+---+---+---+
    a   b   c   d   e   f   g   h

8/8/pp6/3b2K1/1P6/PN2k3/8/8 w - -

[Event "?"]
[Site "?"]
[Date "??.??.????"]
[Round "?"]
[White ""]
[Black ""]
[Result "*"]
[WhiteElo "?"]
[BlackElo "?"]
[FEN "8/8/pp6/3b2K1/1P6/PN2k3/8/8 w - - 0 1"]

1.*

00:00:00  1.01  -2.74   1.Kf5 Bxb3
00:00:00  1.04  -0.85   1.b5 Bxb3 2.bxa6
00:00:00  1.10  -0.23   1.Nc1
00:00:00  2.00  -0.21   1.Nc1 Ke4
00:00:00  3.00  -1.67   1.Nc1 Kd2 2.b5 Kxc1 3.Kf4
00:00:00  3.04  -0.26   1.Na1 Kd3 2.Kf4 b5 3.Ke5 Bf7 4.Kf6
                       Bc4 5.Kg5 Ba2 6.Kh5 Kc3 7.Nb3 Bxb3
                       8.Kg6 Bc2 9.Kg7 Kb2 10.Kf6 Kxa3
                       11.Ke5 Kxb4 12.Kd6  (0)

00:00:01  4.00  -0.23   1.Na1 Kd3 2.Kf4 b5 3.Ke5 Bf7 4.Kf6
                       Bc4 5.Kg5 Ba2 6.Kh5 Kc3 7.Nb3 Bxb3
                       8.Kg6 Bc2 9.Kg7 Kb2 10.Kf6 Kxa3
                       11.Ke5 Kxb4 12.Kd6  (0)

00:00:01  5.00  -0.23   1.Na1 Kd3 2.Kf4 b5 3.Ke5 Bf7 4.Kf6
                       Bc4 5.Kg5 Ba2 6.Kh5 Kc3 7.Nb3 Bxb3
                       8.Kg6 Bc2 9.Kg7 Kb2 10.Kf6 Kxa3
                       11.Ke5 Kxb4 12.Kd6  (1)

00:00:01  6.00  -0.19   1.Na1 Ke4 2.Nc2 Bb3 3.Ne1 Be6 4.a4
                       Kd5 5.Nf3 Kc4 6.Nd2 Kd3 7.Nf3  (1)

00:00:01  7.00  -0.20   1.Na1 Ke4 2.Kf6 b5 3.Nc2 Bc4 4.Ne1
                       Bd5 5.Ng2 Kf3 6.Ne1 Ke4 7.Ng2 Kf3
                       8.Ne1  (1)

00:00:01  8.00  -0.20   1.Na1 Kd3 2.Kf5 b5 3.Kf6 Kc3 4.Ke5
                       Bc4 5.Kf5 Ba2 6.Ke5 Bf7 7.Kf4 Bc4
                       8.a4 bxa4 9.b5 axb5 10.Kg3 a3 11.Kh2
                       Kb2 12.Kg3  (1)

00:00:01  9.00  -0.20   1.Na1 Kd3 2.Kf5 b5 3.Kf6 Kd4 4.Nc2
                       Ke4 5.Ne1 Kd4 6.Nc2 Ke4 7.Ne1 Kd4  (1)

00:00:01 10.00  -1.34   1.Na1 Kd3 2.Kf5 Kc3 3.Ke5 Ba8 4.b5
                       Kb2 5.bxa6 Kxa1 6.Kf5 Kb2 7.a4  (1)

00:00:02 11.00  -1.45   1.Na1 Kd3 2.Kf5 Kc3 3.Ke5 Bg2 4.b5
                       Kb2 5.bxa6 Kxa3 6.a7 Kb4 7.a8  (1)

00:00:04 12.00  -1.96   1.Na1 Kd3 2.Kf5 Kc3 3.Ke5 Bc4 4.a4
                       Kxb4 5.Kd4 Kxa4 6.Kxc4 b5 7.Kd4  (2)

00:00:06 13.00  -1.97   1.Na1 Kd3 2.Kf5 Kc3 3.Ke5 Bc4 4.Kd6
                       Kb2 5.Kc6 b5 6.Kb6 Kxa1 7.Kxa6 Kb2
                       8.Kb6 Kxa3  (4)

00:00:13 14.00  -1.97   1.Na1 Kd3 2.Kf5 Kc3 3.Ke5 Bc4 4.Kd6
                       Kb2 5.Kc6 b5 6.Kb6 Kxa1  (6)

00:00:26 15.00  -2.64   1.Na1 Kd3 2.Kf5 Kc3 3.Ke5 Bc4 4.Ke4
                       b5 5.Ke5 Kb2  (15)


Positions                :      20.617.318
Nodes per second         :         542.561

Extensions (checks)      :         449.153 (2%)
Extensions (captures)    :          56.684 (0%)
Extensions (king safety) :               8 (0%)
Extensions (on depth)    :               0 (0%)
Extensions (remaining)   :          29.565 (0%)
Extensions (total)       :         535.410 (2%)

Hash Table               : 1.505.494  2.342.424  (5%)
Average depth            : 17
Deepest depth            : 37




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