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Subject: Re: computer calculations of number of ways to play first 10-ply

Author: Danniel Corbit

Date: 20:35:35 07/29/98

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On July 29, 1998 at 18:54:35, Robert Hyatt wrote:
[snip]
>Here I have some data.  In the "Crafty goes Deep" experiment last year, we ran
>such a test with Crafty, searching 347 different positions to depth=15.  We
>were interested in how often does one more ply produce a different move.  The
>result?  Somewhere in the 20% range which was surprising.  In fact, within close
>limits, adding one ply changed the PV about 20% of the time no matter whether it
>was going from ply 6 to ply 7, or ply 14 to 15.  The JICCA has the exact
>results, while the raw search output is on my ftp machine...
My original question was if such analysis will choose a move that was not
considered in the top 3 previously.  My position is that from a given starting
point, a ways into the game, there are not dozens of good moves, but only two or
three.  The opinion about which one is best will waffle, but I doubt if a
completely new replacement is found often.
If we take the 20% figure, that means one in 5 times, a new move is chosen.  But
was that move 2% improved over the previous ply, to barely edge out the previous
champion?

I do not believe that there are more than just a few good alternatives, on
average.  I'm probably just stubborn.  In other words, does an additional ply
tend to promote a move that was a dog before?  I simply don't believe it.
Except on very rare occasions.



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