Author: Christophe Theron
Date: 09:45:47 10/30/03
Go up one level in this thread
On October 30, 2003 at 12:43:04, José Carlos wrote:
>On October 30, 2003 at 12:27:16, Tord Romstad wrote:
>
>>On October 30, 2003 at 11:05:41, Uri Blass wrote:
>>
>>>On October 30, 2003 at 10:46:09, Vladimir Medvedev wrote:
>>>
>>>>>>In order to find out how good my move ordering is, I determined to check
>>>>>>which percentage of the cutoffs occured on the first move searched.
>>>>
>>>>Is branching factor more or less accurate parameter to evaluate quality of
>>>>sorting moves?
>>
>>Perhaps, but how do you measure the branching factor? I have asked this
>>question here before, but never recieved any answer.
>
>
> After every iteration I print in my log file something like:
>
> Branching factor:
> - This iteration = Total Nodes / Nodes Last Iteration
> - Acumulated: pow(Total Nodes,1.0 / Depth)
>
> With this measure, I'm finding that my program has huges BF's (per iterartion)
>in the first nodes, that go down to <= 3 after 5 iterations or so. But the
>acumulated has a slow reducing behaviour, going to <= 3 after at least 12 plies.
> I'm still working on understanding it :)
>
> José C.
The QSearch is maybe a part of the reason.
The percentage of QSearch nodes in the first iterations is higher than in the
deeper iterations.
At least that is my experience.
Christophe
>
>
>
>>>You can improve your branching factor by pruning or reduce it by extensions.
>>
>>Everybody always seem to claim that extensions increase the branching factor
>>(I suppose that is what you meant, although you wrote "reduce"), but it is
>>not at all obvious to me why this should be so. On the few occasions I have
>>experimented with this myself, removing all extensions has not resulted in
>>a noticably better branching factor. Of course the program needs fewer
>>nodes to complete a given search depth without extensions, but the difference
>>does not seem to be exponential. Perhaps more detailed and careful
>>experiments would have given a different result.
>>
>>Tord
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