Author: Vincent Diepeveen
Date: 19:08:27 01/26/01
Go up one level in this thread
On January 25, 2001 at 11:05:54, Robert Hyatt wrote: >On January 25, 2001 at 09:49:02, Uri Blass wrote: > >>On January 25, 2001 at 09:34:05, Robert Hyatt wrote: >> >>>On January 25, 2001 at 08:20:26, David Rasmussen wrote: >>> >>>>Howdy. >>>> >>>>Inspired by the thread on extensions, I was wondering whether the idea of >>>>negative extensions or reductions could be a good one. >>>> >>>>I mean, maybe many of the "unsound" pruning methods would be sounder if, instead >>>>of just pruning, they just adjusted the resulting depth down. In that way, a >>>>line would still be examined, only later. >>> >>> >>>This is what null-move search does, in essence... >> >>Not exactly. >> >>I know that some programs cannot solve mate in 2 when it is not a problem of >>depth because they are null movers. >> >>Null move is used also only in cases when there is no threat and the idea of >>negative extensions can be used also in different cases so the idea of negative >>extensions seems to be more general. >> >>Uri > > >Null moves aren't used only when there is no threat. IE if I can play a null- >move, and you can't hurt me at all, then you don't have any threats. But _I_ >might. And it is possible that you have them too, which will generally make >the null-move search fail low and be ignored. Completely depends upon the number of moves you try in the reduced depth. If that reduced depth is that small that it is taken over by qsearch it depends upon how many moves you try in qsearch. If you hardly try moves in qsearch then obviously you will not detect much last few plies.
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