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Subject: Re: Nullmove: when to avoid it?

Author: Robert Hyatt

Date: 10:22:41 02/28/01

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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

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