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Subject: Re: Chess program improvement project (copy at Winboard::Programming)

Author: Nathan Thom

Date: 20:51:29 03/06/06

Go up one level in this thread


On March 06, 2006 at 23:49:15, Dann Corbit wrote:

>On March 06, 2006 at 23:45:06, Nathan Thom wrote:
>
>>On March 06, 2006 at 23:40:58, Stuart Cracraft wrote:
>>
>>>On March 06, 2006 at 23:36:22, Dann Corbit wrote:
>>>
>>>>On March 06, 2006 at 22:14:27, Nathan Thom wrote:
>>>>
>>>>>>>3. Search inefficiency (branching factor of a good program is definitely under
>>>>>>>4)
>>>>>>
>>>>>>  * My branching factor is about 2-3 for these kinds of positions.
>>>>>
>>>>>How are branching factors calculated? I get wildly different values at each ply
>>>>>as each side usually has different numbers of moves available to them... and at
>>>>>the root node, its always the full number of moves isnt it?
>>>>>
>>>>>e.g, for 8/6k1/6Pp/3r1P2/6K1/n3BP2/1p6/4R3 w - - 3 51
>>>>>I get branching factors at each ply of 26 2 20 4 16 3 13 3 10
>>>>
>>>>The simplest and most accurate way to determine your branching factor is to
>>>>divide the time to complete iteration N+1 by the time to complete iteration N
>>>>(don't bother computing it if you had an interrupt halt calculations --
>>>>calculate it only if it finished naturally).
>>>
>>>That's what I do, then I average them all together for the current
>>>iterative deepening 1-N set for the given search.
>>>
>>>After that I average all those averages together across a test suite
>>>to get the final branching factor.
>>>
>>>The former are br= in my listing and the latter are bf= which is an ongoing
>>>average of the averages.
>>>
>>>Stuart
>>
>>ahhh, that would be why mines so different. i actually keep track of the actual
>>number of moves followed at each ply which to me is what branching factor means.
>
>Look at your counts:
>Hi,low,hi,low...
>
>I think it is hash table that does that with your program, but I guess if you
>calculate the time you will not see the same crazy oscillations.
>
>You should not see branching factors near 30 unless you are using mini-max.  Are
>you not using alpha-beta?

Yes im using alpha-beta and such, but no pruning as yet, and my material only
evaluation doesnt really help :)



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