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Subject: Re: Crafty perfectly legal (Bob?)

Author: Uri Blass

Date: 12:57:44 03/16/04

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On March 16, 2004 at 15:12:16, Dan Honeycutt wrote:

>On March 16, 2004 at 14:21:55, Uri Blass wrote:
>
>>On March 16, 2004 at 13:29:02, Dan Honeycutt wrote:
>>
>>>On March 15, 2004 at 16:33:37, David Mitchell wrote:
>>>
>>>>On March 15, 2004 at 08:47:38, Andrew Wagner wrote:
>>>>
>>>>Some intelligence has been found useful however. Crafty is one example of this.
>>>>When Crafty's king is in check, the move generator changes from pseudo-legal, to
>>>>perfectly legal move generation, only.
>>>
>>>my move generation is patterned after Crafty and Pepito (except i do legal move
>>>generation) so i'm pretty familiar with Crafty's move generation.  to do legal
>>>move generation you have to look at pins on the piece moving - which Crafty does
>>>with the king in check.  you also have to look at pins on the captured piece in
>>>the case of an enpassant capture - if removal of the captured pawn will uncover
>>>an attack on the king.  i may be wrong, but i don't think Crafty does that.
>>>
>>>Dan H.
>>
>>I do not understand
>>I did not learn the code of Crafty but I do not see an example when
>>the king is under attack and the legality of enpassant capture is changed
>>because of a pin that is not a pin of the pawn that is moving.
>>
>>Can you give a diagram when you think crafty does not generate all the legal
>>moves when the king is in check?
>>
>>Uri
>
>I was thinking of something like:
>   r   K
>     p P
>   b
>Where PxP ep blocks the rook attack but uncovers an attack by the bishop.  but
>that makes no sense because the king would have been attacked by the bishop
>before the pawn move.
>
>completely unrelated, how do you make those nice position diagrams that
>everybody but me knows how to use?
>Dan H.

I simply post a fen and add [D] behind the fen.

Uri



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