Author: Uri Blass
Date: 02:22:18 08/31/02
Go up one level in this thread
On August 30, 2002 at 23:00:30, Andreas Herrmann wrote: >On August 30, 2002 at 21:03:25, Uri Blass wrote: > >>On August 30, 2002 at 17:24:34, Andreas Herrmann wrote: >> >>>On August 30, 2002 at 14:33:08, Omid David wrote: >>> >>>>On August 30, 2002 at 14:27:53, Andreas Herrmann wrote: >>>> >>>>>On August 30, 2002 at 09:56:21, Omid David wrote: >>>>> >>>>>>On August 29, 2002 at 23:03:43, Dann Corbit wrote: >>>>>> >>>>>>>On August 29, 2002 at 22:50:53, Brian Richardson wrote: >>>>>>>[snip] >>>>>>>>Is move sorting turned off in Yace, GLC and Gnu for the depth = 6 searchs? >>>>>>> >>>>>>>Pretty irrelevant since all of them show a branching factor between 2 and 3 for >>>>>>>the opening position. >>>>>>> >>>>>>>The program described by the OP had a branching factor of 6-8, IIRC. >>>>>>> >>>>>>>IOW, something is clearly amiss. >>>>>>> >>>>>>>I wonder how often the OP finds the requested position in the hash table. >>>>>>>Usually, hash table alone would be enough to prevent a branch factor that >>>>>>>terrible. >>>>>> >>>>>>How do you calculate branching factor here? >>>>> >>>>>A branching factor of 3 means that each node has in the average 3 child nodes >>>>>(This is the description i have found on an internet page). So the formula must >>>>>be: >>>>> >>>>>bf = ( Nodes [ply n] - nodes [ply n-1] ) / nodes [ply n-1] >>>>> >>>>>Excample: >>>>>Whole nodes until ply 5 = 4000 and whole nodes until ply 6 = 20000. >>>>>Then you got a branching factor of >>>>>bf [ply 6] = ( 20000 - 4000 ) / 4000 = 4.0 >>>>> >>>>>have a nice day >>>>>Andreas >>>> >>>>I know this :-) >>>> >>>>But there is the odd/even issue, so the b-factor can change drastically while >>>>moving from an odd ply to an even ply, and vice versa. >>> >>>I think the best is to calculate an average branching factor from all plys. >>> >>>bf[avg] = ( bf[2] + bf[3] + bf[4] ... + bf[n] ) / (n - 1) >>> >>>Andreas >> >>It is better to use >>( bf[2] * bf[3] * bf[4] ... * bf[n] )^(1/(n-1)) >> >>Uri > >Hi Uri, > >have you found an official description of the calculation of the branching >factor in search trees? Because i don't know how to calculate the branching >factor correct. My formulas i have created only based on the description >"A branching factor of 3 means that each node has in the average 3 child nodes" >that i have found on an internet page. My formula is based on common sense and not on a link in the internet. I want the branching factor to tell me which program is faster in getting deeper. If I use your formula I can get misleading information because it is better to have a branching factor of 2 at even plies and 4 in odd plies and not 3 in all plies and your formula suggest that it is the same. Uri
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