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Subject: Re: It is a nullmove killer (zugzwang)

Author: Dan Homan

Date: 06:53:23 11/05/99

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On November 05, 1999 at 09:28:30, Rémi Coulom wrote:

>On November 05, 1999 at 08:46:59, Bernhard Bauer wrote:
>
>>On November 05, 1999 at 06:31:49, Howard Exner wrote:
>>
>>>1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2
>>>Input this into Crafty and where it goes.
>>>White has to take care not to fall into a drawn ending with the
>>>eventually advanced black rook pawn. Also the KQN vs kq should be avoided.
>>>I tried what looked like good defenses for black but always came up a move
>>>or two short
>>>of drawing. If black just goes ahead and advances the a pawn white will
>>>capture the g7 pawn with the king and win by one tempo. Those endgame tablebases
>>>should come in handy.
>>
>>Thank you for your explanation. The line you give seams good.
>>A human analysis is still better than anyone done by a computer.
>>Anyway it would be interesting to know what other programs think.
>>Kind regards
>>Bernhard
>
>After 1. b5+ Qxb5 2. Nd3, black is in zugzwang. A program that does not do the
>null move should find 1. b5+ at depth 5 or so.
>
>Remi

You are right.  With Null-Move ON, I can't solve this; however, with
Null-Move OFF, my program gives.....

White-To-Move[1]: setboard 4q/p5p/k5P/8/1PN4K/8/1N2B/8 w - -
White-To-Move[1]: analyze
Analysis mode: Enter commands/moves as ready.

  1.  -0.29     0        5   1. b5+
  1.   0.69     0       20   1. Ne5+
  1.   0.74     0       38   1. Bh5
  1.   0.83     0       39   1. Bd3
  1.   0.83     0       47   1. Bd3
  2.  -0.09     0       97   1. Bd3 Qe7+
  2.   0.68     0      373   1. Ne3+ Kb7
  2.   0.76     0      623   1. Ne5+ Kb6
  2.   0.76     0      625   1. Ne5+ Kb6
  3.   0.77     0     1067   1. Ne5+ Kb7 2. Bf3+
  3.   0.77     0     1757   1. Ne5+ Kb7 2. Bf3+
  4.   0.72     0     3029   1. Ne5+ Kb7 2. Nbd3 Qd8+
  4.   0.72     0     6498   1. Ne5+ Kb7 2. Nbd3 Qd8+
  5.   0.67     0    23379   1. Ne5+ Kb6 2. Nbd3 Qe7+ 3. Kh5
  5.   0.67     0    35024   1. Ne5+ Kb6 2. Nbd3 Qe7+ 3. Kh5
  6.   0.70     0    61289   1. Ne5+ Kb6 2. Nbd3 Qb5 3. Kg5 a5
  6.   3.08     0    69020   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Kb5
  6.   3.08     0   104884   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Kb5
  7.   3.08     0   126097   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2
  7.   3.08     1   266906   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2
  8.   2.30     2   350220   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2 Kb6
  8.   2.30     4   864629   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2 Kb6
  9.   2.33     6  1073705   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2 Kb6
                             5. Kg5
  9.   2.33    14  2261235   1. b5+ Qxb5 2. Nd3 Qxc4+ 3. Nf4 Qxe2 4. Nxe2 Kb6
                             5. Kg5
 10.   5.47    23  3850853   1. b5+ Qxb5 2. Nd3 Qb8 3. Nc5+ Kb5 4. Ne5+ Kc5
                             5. Nd7+ Kd6
 10.   5.47    47  7441622   1. b5+ Qxb5 2. Nd3 Qb8 3. Nc5+ Kb5 4. Ne5+ Kc5
                             5. Nd7+ Kd6
 11.   5.48    60  9885919   1. b5+ Qxb5 2. Nd3 Qb8 3. Nc5+ Kb5 4. Ne5+ Kc5
                             5. Nd7+ Kd6 6. Nxb8
 11.   5.48   131 19784897   1. b5+ Qxb5 2. Nd3 Qb8 3. Nc5+ Kb5 4. Ne5+ Kc5
                             5. Nd7+ Kd6 6. Nxb8


 - Dan




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