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Subject: Re: Look at this !!(??) move by Crafty 18.14!

Author: Uri Blass

Date: 00:38:12 03/29/02

Go up one level in this thread


On March 28, 2002 at 22:02:09, Robert Hyatt wrote:

>On March 27, 2002 at 11:44:46, Uri Blass wrote:
>
>>On March 27, 2002 at 09:59:05, Robert Hyatt wrote:
>>
>>>On March 27, 2002 at 07:18:09, Aaron Tay wrote:
>>>
>>>>On March 27, 2002 at 06:55:43, James T. Walker wrote:
>>>>
>>>>>On March 27, 2002 at 05:28:28, Jouni Uski wrote:
>>>>>
>>>>>>[D]8/B5pp/4k3/P7/6n1/8/P6P/7K b - - 0 41
>>>>>>
>>>>>>Crafty as black played Nxh2!!(??). Yes the game ended draw so the move is
>>>>>>probably correct, but I doubt, that Crafty's evaluation really understand this.
>>>>>>E.g. if white plays a6 then black has no way to a8 square...
>>>>>
>>>>>*******
>>>>>You can't have it both ways!  If the move is correct then a6 means nothing.  If
>>>>>a6 wins then Nxh2 is definitely wrong.  Can you prove that a6 wins?  Crafty is
>>>>>counting on the Bishop not covering the a8 square I guess.  But this could be
>>>>>one of the exceptions to the rule if you can prove that a6 wins.  The black King
>>>>>must head for c7/c8 so it can get to b8 then a8 if the Bishop moves.  I suspect
>>>>>it all hangs on a tempo.  How is the lone King to stop the two connected passed
>>>>>pawns without moveing the Bishop?
>>>>>********
>>>>
>>>>[D]8/B7/4k3/P7/6n1/8/P6P/7K b KQkq -
>>>>
>>>>Remove black's 2 passed pawns and it still thinks Nxh2 is good with a near draw
>>>>score..Eventually (21 seconds on mine,depth 18) crafty 18.13 sees the loss after
>>>>Nxh2 but there is nothing better..
>>>>
>>>>I guess the rule does have a problem..
>>>>
>>>>
>>>>Aaron
>>>
>>>Mine doesn't play Nh2 in the above position.  This now becomes a zugzwang
>>>position with no black pawns to move, which turns it into a trivial mate for
>>>white...
>>
>>I guess that it does not play Nxh2 because of tablebases.
>>
>>I wonder what happens when  you add a third pawn for white in the a file.
>>
>>Uri
>
>
>No idea... but so long as black has something besides the king, this is a
>draw...

Not exactly
It seems that if black has 2 connected pawns then it is a draw
but one pawn does not mean a draw because white can
first capture the pawn and later win by zunzwang.

Uri



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