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Subject: Re: Nice end-game problem; here is another phenomenon, who can explain?

Author: blass uri

Date: 02:48:00 04/28/99

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On April 28, 1999 at 05:34:41, blass uri wrote:

>
>On April 28, 1999 at 05:04:14, Harald Faber wrote:
>
>>On April 27, 1999 at 13:25:15, Jeremiah Penery wrote:
>>
>>>>>
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    8  | *Q| *N| *B|   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    7  |   | *P|   | *K| B | K |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    6  | *P| P | *P|   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    5  | P |   | *P|   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    4  |   |   | P |   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    3  |   |   |   |   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    2  |   |   |   |   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>    1  |   |   |   |   |   |   |   |   |
>>>>>       +---+---+---+---+---+---+---+---+
>>>>>         a   b   c   d   e   f   g   h
>>>>>
>>>>>How can a black bishop move to e5 or e7 in this position?
>>>>>I see only one black bishob on c8. This bishop can not move anywhere.
>>>>>Can you enlighten me please?
>>>>>
>>>>>Kind regards
>>>>>Bernhard
>>>>
>>>>Argh! Amazing what can go wrong...put the WHITE BISHOP back to f6 and then WHITE
>>>>TO MOVE. Now Be7 wins while Crafty and Fritz, well, you know what...
>>>
>>>Here is my output (WITH nullmove - I have not changed anything about nullmove in
>>>the code)
>>>8->   0.17   7.14   1. Be7 Qa7 2. bxa7 Kc7 3. a8=Q Nd7
>>>                    4. Kg7 Ne5
>>>9     0.18     --   1. Be7
>>>9     0.22     ++   1. Be7!!
>>>9     0.57  Mat06   1. Be7 Qa7 2. bxa7 Kc7 3. Bd6+ Kxd6
>>>                    4. axb8=Q+ Kd7 5. Qe5 b5 6. Qe7#
>>>9->   0.58  Mat06   1. Be7 Qa7 2. bxa7 Kc7 3. Bd6+ Kxd6
>>>                    4. axb8=Q+ Kd7 5. Qe5 b5 6. Qe7#
>>>
>>>Jeremiah
>>
>>Hmm. So is there a difference between the Fritz-engine and the "normal" Crafty?!
>>The engine has Be5.
>
>The engine has Be7 if you give it only the ginal position and not all the game

The engine also has Be7 if you give it all the game and 3 options instead of 1.

When you give the engine all the game it simply see that Be5 is a draw with
repetition and Be7 has no threat.

When you give the engine only the final position then Be5 is no repetition so
crafty has not enough time to see that Be5 is drawing, check Be7 and discovers
that it is winning.

Uri




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