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Subject: Re: Nullmove: when to avoid it?

Author: Josť Carlos

Date: 16:03:46 02/28/01

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On February 28, 2001 at 16:55:52, Robert Hyatt wrote:

>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.
>>>>>Leen
>>>>
>>>>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.
>>>>
>>>>Miguel
>>>
>>>
>>>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
>>>lose.
>>
>>  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.
>>
>>  Josť C.
>
>
>That isn't quite good enough.  In the position I gave the bishop has that many
>available squares.  Except that most lose...

  Of course. I didn't read carefully enough your example :(
  But anyway, could it be used added to some other critea (number of pieces,
etc...)?

  Josť C.



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