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Subject: Re: Branching factor

Author: Randall Shane

Date: 06:59:48 10/17/05

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On October 17, 2005 at 06:12:48, chandler yergin wrote:

>On October 16, 2005 at 10:02:12, Tord Romstad wrote:
>
>>On October 16, 2005 at 08:18:48, Maurizio De Leo wrote:
>>
>>>I tought the branching factor of modern programs was more of the order 3.5. Is
>>>the 2.4 value typical of Fruit, or is it due to the particulare position, or I
>>>was just wrong and most modern programs have a branching factor smaller than 3 ?
>>
>>I think you are just wrong.  I am fairly sure most modern programs have an
>>average branching factor closer to 2 than to 3 in the middle game.
>>
>>Tord
>
>  The Branch Tree is usually about 35 Branches from any  position

Full trees from normal positions tend to have a branching factor averaging about
35, that's true, but that's not the issue here.

All but the simplest chess problems implement some form of alpha-beta searching
to cut down on the branching factor.  The entire tree doesn't have to be
searched to 'prove' a proposed move at a level is best.

Naive implementations of alpha-beta can be expected to have a branching factor
of about 6 in most positions.  Using good move ordering, hashing, pruning, and
many other techniques can reduce this further.  The flow of the conversation
above your reply concerned how far the branching factor had been reduced.




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