Author: Howard Exner
Date: 00:20:53 02/17/99
Go up one level in this thread
On February 16, 1999 at 22:44:16, Dann Corbit wrote:
>On February 16, 1999 at 22:00:15, Jeremiah Penery wrote:
>
>>On February 16, 1999 at 21:17:30, Howard Exner wrote:
>>
>>>On February 16, 1999 at 18:56:17, John Stanback wrote:
>>>
>>>>On February 15, 1999 at 20:48:35, Howard Exner wrote:
>>>>
>>>>>On February 15, 1999 at 03:22:50, Jouni Uski wrote:
>>>>>
>>>>>>In was quite surprised, that in two consecutine(!) tournament game between
>>>>>>Junior 5 and Crafty 16.3 Junior eats a7 pawn with bishop. So after b6 bishop is
>>>>>>lost. I have never seen Mchess or Rebel even considering that. Hmmm...
>>>>>
>>>>>7k/ppp1bpp1/7p/8/8/1P1PB2P/1P3PP1/5K2 w
>>>>>
>>>>>Is this the kind of example you were considering?
>>>>>Sometimes its ok to take the pawn as the bishop can escape
>>>>>but in the above example it would be a relatively easy task for
>>>>>a human to avoid the move Bxa7. How do programs handle this position?
>>>>
>>>>Zarkov has knowledge for this and does not take the pawn, but plays Ke2.
>>>>
>>>>John
>>>
>>>I tried this on Rebel 10 but it stuck to Bxa7 even after an hour (K6-233).
>>>I'm glad someone posted there results on this one as I think code for this
>>>is essential. Will the code also prevent taking such a pawn when it is the
>>>right choice? Or is it a type of code/knowledge that plays the odds?
>>
>>I tried it in Crafty, which HAS the code, and it still played Bxa7! Any
>>explanation on this?
>I'm no genius, but it looks like Crafty makes the kick save to me. Here is how
>I saw the race from my standpoint (safe to take it):
>[Event "?"]
>[Site "?"]
>[Date "?"]
>[Round "-"]
>[White "?"]
>[Black "?"]
>[Result "*"]
>[FEN "7k/ppp1bpp1/7p/8/8/1P1PB2P/1P3PP1/5K2 w - - 0 1"]
>[SetUp "1"]
>
>{--------------
>. . . . . . . k
>p p p . b p p .
>. . . . . . . p
>. . . . . . . .
>. . . . . . . .
>. P . P B . . P
>. P . . . P P .
>. . . . . K . .
>white to play
>--------------}
>1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 Kg8 4. Ke3 Kf8 5. Kd4 Ke8 6. Kd5 Kd8 7. Kc6
>Kc8 8. Ba7
>*
>And here is Crafty's analysis:
>clearing hash tables
>time surplus 0.00 time limit 30.00 (3:00)
>depth time score variation (1)
> 7 0.10 0.34 1. Bxa7 Bf6 2. Bb8 c6 3. Bd6 Bxb2 4.
> Ke2
> 7-> 0.13 0.34 1. Bxa7 Bf6 2. Bb8 c6 3. Bd6 Bxb2 4.
> Ke2
> 8 0.16 0.16 1. Bxa7 Bf6 2. Bb8 c6 3. Bd6 Bxb2 4.
> Ke2 Kh7
> 8-> 0.30 0.16 1. Bxa7 Bf6 2. Bb8 c6 3. Bd6 Bxb2 4.
> Ke2 Kh7
> 9 0.42 0.25 1. Bxa7 Bf6 2. Bb8 c6 3. Bd6 Bxb2 4.
> Ke2 Kh7 5. Ke3
> 9-> 0.56 0.25 1. Bxa7 Bf6 2. Bb8 c6 3. Bd6 Bxb2 4.
> Ke2 Kh7 5. Ke3
> 10 0.76 0.22 1. Bxa7 Bf6 2. Bb8 c6 3. f4 Bxb2 4.
> Be5 Bc1 5. Ke2 Kh7
> 10-> 1.49 0.22 1. Bxa7 Bf6 2. Bb8 c6 3. f4 Bxb2 4.
> Be5 Bc1 5. Ke2 Kh7
> 11 3.18 0.33 1. Bxa7 Bf6 2. d4 g5 3. Ke2 Kg7 4.
> Ke3 g4 5. Bc5 gxh3 6. gxh3 Kg6
> 11-> 4.18 0.33 1. Bxa7 Bf6 2. d4 g5 3. Ke2 Kg7 4.
> Ke3 g4 5. Bc5 gxh3 6. gxh3 Kg6
> 12 8.20 0.38 1. Bxa7 b6 2. d4 Bd6 3. Ke2 Kh7 4.
> Ke3 Kg6 5. Bb8 b5 6. d5 Kf5
> 12-> 12.64 0.38 1. Bxa7 b6 2. d4 Bd6 3. Ke2 Kh7 4.
> Ke3 Kg6 5. Bb8 b5 6. d5 Kf5
> 13 26.16 0.43 1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 Kh7 4.
> Ke3 Kg6 5. Ke4 h5 6. d4 f5+ 7. Kd5
> Kf6
> 13-> 34.35 0.43 1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 Kh7 4.
> Ke3 Kg6 5. Ke4 h5 6. d4 f5+ 7. Kd5
> Kf6
> 14 55.38 0.39 1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 Kh7 4.
> Ke3 f5 5. d4 Kg6 6. d5 Kf6 7. b4 Ke5
> 14-> 1:32 0.39 1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 Kh7 4.
> Ke3 f5 5. d4 Kg6 6. d5 Kf6 7. b4 Ke5
> 15 2:47 0.38 1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 g6 4.
> Ke3 f5 5. d4 Kg7 6. d5 Kf6 7. f4 g5
> 8. fxg5+ hxg5 9. Kd4
> 15-> 4:17 0.38 1. Bxa7 b6 2. Bb8 Bd6 3. Ke2 g6 4.
> Ke3 f5 5. d4 Kg7 6. d5 Kf6 7. f4 g5
> 8. fxg5+ hxg5 9. Kd4
> 16 11:24 0.40 1. Bxa7 b6 2. Ke2 f5
Instead of f5 manually play for black by moving the king towards the trapped
bishop. The black king should get there in time to capture the bishop. That's
why I put the black king so far away in order to make it more difficult. I
did not want it to be solved by search alone but by some kind of code that
recognizes how dangerous it is to have the bishop trapped.
3. Ke3 Bc5+ 4.
> d4 Bd6 5. Bb8 g5 6. b4 Kg7 7. d5 Bf4+
> 8. Kd3 Kf6 9. g3 Be5
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