Author: Ulrich Tuerke
Date: 06:53:44 03/31/02
Go up one level in this thread
On March 31, 2002 at 06:17:15, Klaus Friedel wrote:
>Has anybody ever tried something like that in his null move code :
>
>
> int nullDepth = depth - (NULL_REDUCE + 1)*DEPTH_BASE;
>
> if(tryNull){
> executeNullMove();
> beta -= NULL_BONUS;
> value = - search(nullDepth, -beta, -beta+1, ply + 1);
> undoNullMove();
> if(value >= beta){
> beta += NULL_BONUS;
> ttStore();
> return beta;
> }
> beta += NULL_BONUS;
> }
>
>
>Bigger values of NULL_BONUS increase the count of nodes prunded (but you migth
>oversee some tactics). Values of about 30cp made my engine ply slightly better
>than the default null-move (NULL_BONUS = 0).
I think that this is a rather old idea, afaik this was first suggested by
Goetsch and Campbell in their original paper about the null-move.
I've played around a bit with this some years ago. In my experiments, the gain
had always been very modest although not without risk.
As already remarked in this thread, for most programs of today, this idea isn't
interesting anyway, because most engines are performing minimum window searches.
Uli
>
>
>Klaus
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