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Subject: Re: Buggy check extensions, MAXPLY

Author: Uri Blass

Date: 03:49:56 03/21/03

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On March 21, 2003 at 05:21:18, Albert Bertilsson wrote:

>>I agree that at the level of your program more than 50 plies are not needed but
>>I am surprised that you get more than 50 plies with only check extension and bad
>>move ordering.
>>
>>Maybe you should ask your program to print for you the line of 50 plies that it
>>gets.
>>
>>If you search 50 plies than at depth 10 you should have 30 checks out of the
>>first 40 moves even if you have 10 captures in the qsearch and it always almost
>>does not happen because usually the opponent does not reply to check by a check
>>and having 10 captures in the qsearch is also rare.
>>
>>Uri
>
>I've only noticed this happening very few times, actually without check
>extensions, but the general situation when it happens:
>Both sides have a piece that they need to protect or defend, if they don't the
>loose almost immediatly. So the line is a series of moves from both sides trying
>to vary their game to push the inevitable draw forward. When this happens in a
>game some 20 very similar moves are played, that only very slightly avoids the
>draw by repetiotion. Then the game usally ends by a draw, or that the pieces are
>both captured, and then only two kings or something like it are left on the
>board.

The only situation when a side need to defend a piece is if the opponent threats
that piece.

I do not understand the logic of having threat extensions when you do not have
even check extensions.

Check is a private case of threat(threat on the king) and deciding to extend
only threats against other pieces does not make sense.

extending every threat by a full ply does not make sense and it may cause the
tree to explode

Uri



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