Computer Chess Club Archives




Subject: Re: Proving something is better

Author: Bruce Moreland

Date: 11:31:21 12/18/02

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On December 18, 2002 at 11:29:37, Omid David Tabibi wrote:

>On December 18, 2002 at 11:23:38, Gian-Carlo Pascutto wrote:
>>On December 18, 2002 at 11:15:01, Omid David Tabibi wrote:
>>>I further don't understand why all the fire is directed at me; fixed depth
>>>comparisons are the common accepted comparison methods, which are completely
>>>hardware independant.
>>>For the most recent examples take a look at Heinz and Plaat's numerous >articles, all of which were conducted in fixed depth.
>>I would think that the best research is the one that improves upon
>>the mistakes of previous ones.
>I am yet to be convinced that the methodology practiced by Hyatt, Schaeffer,
>Marsland, Buro, Plaat, Heinz, and others, is mistake.

I have complaint with how this is applied, sometimes.

One type of test involves making the tree smaller, period, while doing the same
kinds of work.  If Schaeffer is going to test the history heuristic, that's
great -- if the tree is smaller, it's a win, because if you can consistently do
the *same* stuff in fewer nodes, that's always good.

The only possible criticism I can have of something like this is if it doesn't
use enough test positions.

If you are trying to prove that something sees more, what does seeing more mean?
 You can blow the tree size up by extending everywhere, and you will see more in
a given depth.  But depth is not the proper measure, since a larger tree size
will also take more time to search.

If you want to "improve" a chess program in this manner, just incorporate a
two-ply search into your eval function.  You'll find stuff two plies sooner.

The only reason that your experiment shows that VR=3 is better than R=2 is that
the solution set was bigger *and* the node counts were smaller.  You can
*assume* from that that the times are also reduced.

You can't make these assumptions about R=3 as compared with VR=3.  And for that
matter, you can't make them about R=3 as compared with R=2, given the data you

Your data strongly implies that R=3 is better than R=2.  That is disturbing,
since your paper regards the superiority of R=2 over R=3 as axiomatic.


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