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Subject: Re: NULL MOVE

Author: Sylvain Lacombe

Date: 13:52:32 02/24/99

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On February 24, 1999 at 15:37:58, Don Dailey wrote:

>On February 24, 1999 at 01:16:56, Sylvain Lacombe wrote:
>>I just finished implementing the null move. At first, i thought it wasn't saving
>>much time. Then, i reallize that it does save alot, but only at deeper plys. On
>>the first few plys, i think, it evens slow me down. Is that normal? Am i doing
>>something wrong?
>>I don't use the null move at the first ply, only at the second. It save about
>>40% reaching deep 6. But it takes about 10% more for reaching deep 3 and 4.
>>Hope, you can help.
>This sounds to me as if you are doing something less than optimal
>near end nodes.  The issue is what do you do when you only have
>1 or 2 ply left to search anyway?  Do you go into quies or call
>your main search again?  It's easy to get this wrong if you are
>not careful.  "Wrong" doesn't mean a broken program, it means
>something much less than optimal.

I go in quiescence when there is no more plys to search (depth=0).
Except for the razoring tricks. If at depth = 1 the eval tell me that it's not
going very good, then i jump to quesc instead. What i call nodes is when
quiescence return. When depth = 0, i'm near the end nodes. Is that what you

>My program is a mixture of static rules and null move.  I do null
>move when I have significant depth remaining, but when I am near
>end nodes I do a simple static attack analysis.  This has proven
>to be a significant improvement to my chess program.  It is faster
>than null move and slightly riskier, but the net affect is
>a stronger chess program (for me.)   Even though it's probably
>riskier, it does pick up things null move will miss although the
>converse is also true.
>- Don

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