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Subject: Re: Branche factor

Author: Bert van den Akker

Date: 15:57:56 11/21/99

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On November 21, 1999 at 16:37:52, Daniel Clausen wrote:

>Hi
>
>On November 21, 1999 at 16:04:39, Peter Kappler wrote:
>
>>On November 21, 1999 at 14:59:53, Bert van den Akker wrote:
>>
>>>From the start position I get a branche  factor of about 14%
>>>
>>>This is in a 10 ply search from the start position.
>>>
>>>The branche factor is defined as:
>>>
>>>(total_number_of_moves_looked_at_in_a_node_before_cutoff /
>>>total_number_of_generates_moves) * 100
>>>
>>
>>This is how I used to compute branching factor, too.  I still think it's the
>>best way to measure the quality of your move sorting.
>
>I've no "experience" in computing a branching factor, but this formula looks a
>bit
>strange to me. I would have expected an absolute number, not a percentage.
>
>And consider the following: Let's say you try the move in the hashtable first
>and you
>get a cuttoff. (That's what you want in most cases.) According to your formula
>you
>get a branching factor of 100% - I think you'd like to get a small percentage
>though!
>
>>But, I think most programmers measure branching factor by dividing the total
>>number of nodes search at depth n by the number searched at depth n-1.
>
>This formula seems to be very intuitive to me.
>
>Kind regards,
> -sargon


Before I try the hash move I first generate all moves.
So the percentage will be ok.

In my example on ply 10
27632 moves from the hashtable were causing a cutoff.

Not generating all moves would save me around 0.15 second.

My move generator can generate 200000 times all moves in the start
position.

BvdA








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