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Subject: Re: Hmmm...

Author: Ralf Elvsén

Date: 16:32:50 02/26/01

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On February 26, 2001 at 16:29:06, Severi Salminen wrote:

>>I not so sure about my figure 8.5 anymore. In fact I think the
>>probability that it is correct is pretty low... I locked on
>>that solution immediately and then it's hard to change
>>ones mind. So concerning the theoretical number derived
>>from a branching factor, forget what I said (I'll maybe
>>come back). My advice is still to use measured numbers.
>>This is what I do myself. It has the additional benefit
>>of avoiding my sloppy calculations :)
>
>I think the point of the original message was to make a decent test that
>measures the speed of movegen+makemove. So, if modern chess programs have
>effective branching factor of about 3 (maybe 2-4) it is wise to generate all
>moves and make and unmake three of them. This has nothing to do with critical AB
>tree but normal searching conditions. I'd guess 3 would be good approximation.
>
>Severi

And that is exactly the question I tried to address. Given an (effective)
branching factor, what is the proportion of makemove/movegen ?
Have I been so unclear? I'm not sure if this ratio
equals the branching factor. I'll have a look at it when I have
the time. I guess someone around here knows but is too lazy to
answer.

As I understood the original question he wanted to run one movegen
and then a number of make/unmake in the same proportion as will
be found in a real search. He used a branching factor (however
it was measured) to guesstimate the proportion. I doubted, and still
do, that that is correct (even for a "normal search"). If it is
the obvious thing to do I will be happy to be informed why.
But all those considerations can be skipped
if the proportion is measured. When I do a test like that I don't
care about the branching factor, I don't see the relevance.

Ralf



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