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Subject: Re: Is the Depth directly proportional to the program's strength? (YES!)

Author: Tony Werten

Date: 05:42:00 02/06/02

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On February 03, 2002 at 17:25:48, Wylie Garvin wrote:

>On February 03, 2002 at 13:32:42, William H Rogers wrote:
>
>>Here is an item from Chess Skill in Man and Machine
>>One of the first programs written for computers and later turned into Deep Blue
>>well, I least I think that it lead to Deep Blue.
>>The ran a series of 300 games, playing the program against itself with only
>>different ply settings to see the difference in playing strength.
>>Here are the results:
>>
>>    Rate  P4    P5    P6    P7    P8    P9
>>P4  1235  --    5.0          .5    0     0
>>P5  1570  15   --    3.5    3.0   .5     0
>>P6  1826  19.5 16.5  ---    4.0  1.5    1.5
>>P7  2031  20   17    16     ---  5.0    4.0
>>P8  2208  20   19.5  18.5  15.0  ---    5.5
>>P9  2328  20   20    18.5  16.0 14.5    ---
>>
>>As you can see in the lower ply numbers the program gained the most strenght,
>>but as the ply level got higher the rating increase became smaller and smaller.
>>It would be nice to see some math on a curve to estimate the over all effects.
>>Bill
>
>Hi,
>   There's a 1997 paper by Schaeffer et. al. that refutes the idea that the
>increase in strength is constant per ply at high search depths.  They suggest
>that there are diminishing returns for deeper search, and that previous research
>didn't reveal it simply because chess programs make lots of evaluation mistakes.

They are wrong. Suppose my program does get twice as strong with every extra
ply. How are you going to measure it ?

We play 10 games. First I win 1, then I win 2, then 4, then 8. Quite impossible
for me to keep improving at this level !

So what happens is I win 1,2,4,7,8.5,9 even if my program does get twice as
strong with every extra ply. Then I write a paper claiming my program only
gained .5 points with the last extra ply and call it diminishing returns.

Tony

>
>http://citeseer.nj.nec.com/junghanns97diminishing.html
>
>http://citeseer.nj.nec.com/rd/0%2C17407%2C1%2C0.25%2CDownload/http%253A%252F%252Fciteseer.nj.nec.com/compress/0/papers/cs/1444/http%253AzSzzSzwww.cs.ualberta.cazSz%257EandreaszSzPaperszSzdim.ps.gz/junghanns97diminishing.ps
>
>regards,
>Wylie



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