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Subject: Re: Crafty perfectly legal (Bob?)

Author: David Mitchell

Date: 16:10:10 03/16/04

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On March 16, 2004 at 15:57:44, Uri Blass wrote:

>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

To most of us, that [d] or [D] would be _before_ the fen. But to clarify, the
[d] (or [D], goes immediately (no space afterward), to the _left_ side of the
fen, e.g.:
[d]rnbqk3/ppp5/8/8/8/8/PPPP4/RNBQK3 w --

dave



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