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Subject: Re: Nullmove: when to avoid it?

Author: Miguel A. Ballicora

Date: 11:52:59 02/28/01

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On February 28, 2001 at 13:32:34, Josť Carlos wrote:

>On February 28, 2001 at 13:22:41, Robert Hyatt wrote:
>>On February 28, 2001 at 11:10:30, Miguel A. Ballicora wrote:
>>>On February 28, 2001 at 05:56:36, Leen Ammeraal wrote:
>>>>I am not sure about when to avoid nullmoves.
>>>>I omit it:
>>>>a. when in check
>>>>b. when there are less than 5 pieces (including pawns) on the board
>>>>c. when the last move was a nullmove
>>>>d. at the root node
>>>>Should I also omit it in some other cases,
>>>>for example, when any hashmove (even with a low draft) was found,
>>>>or when beta = alpha + 1?
>>>>Thanks in advance for any help.
>>>Hi Leen,
>>>Regarding b, I do not know whether what I am doing now is correct but I think
>>>that works for me:
>>>When either black or white had no "long range" pieces (bishop, rook or queen)
>>>I disable null move. The rationale is that one side cannot waste
>>>a tempo in a given position having pawns, king and/or knights making the
>>>position prone to have a zugswang.
>>That seems dangerous.  you are white, with a bishop on d5.  I am black and I
>>have a pawn on a7 and g7.  The bishop is zugged here.  If your king can't move,
>>you lose even though you have a long-range slider on the board.  And null move
>>will fail high here naturally as not moving is better than having to move and
>  I don't use null move, so this could be nonsense, but maybe mobility (number
>of available moves) could be used as a threashold for null-move use. For
>example, don't do null-move unless you have at least 10 available moves.

At the first look I thought it was an interesting idea! but it does not
work in the example above...


>  Josť C.

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