Author: Dieter Buerssner
Date: 05:54:12 06/19/01
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On June 19, 2001 at 00:38:34, Robert Hyatt wrote: >On June 18, 2001 at 15:46:13, Bas Hamstra wrote: >>Not at all. Have you never tried Crafty without nullmove? See below my engine >>output, rootposition. Where is the 6? I have never had 6, in my opinion 4,5 on >>average is normal. >> > >The "norm" is sqrt(W) where W is the number of moves at a position in the >tree. In the middlegame, this is around 40 to 50. In the endgame, much >less. The simple formula for total nodes searched will convince you that >one more ply takes sqrt(W) more nodes. I think, this is only true without hashtables. Not only pruning techiques, also hashtables should decrease the branching factor. I cannot remember any quatative data of this effect, but it may be enough to explain the number Bas has given. Also, without hash-tables, without pruning but with search extensions, I think even a higher branching factor has to be expected, because the "average search depth" (however you define this ...) will be larger than the shown search depth. Adding some plies depth will add these plies at least, but also some more nodes due to the more extensions. Regards, Dieter
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