Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Branching factor, etc

Author: Andreas Herrmann

Date: 14:24:34 08/30/02

Go up one level in this thread


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




This page took 0.01 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.