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Subject: Re: Ply Ratings

Author: John Coffey

Date: 22:59:11 09/30/98

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On October 01, 1998 at 01:19:20, Jim Phillips wrote:

>On September 29, 1998 at 21:02:06, Jim Phillips wrote:
>
>>On September 29, 1998 at 14:00:40, William H Rogers wrote:
>>
>>>Has anyone done any research on the ratings that a program has at different
>>>plys?
>>>I once saw a test of chess 4.7 and they had some preliminary ratings on their
>>>program at different ply levels. They could set the depth that their program
>>>would search, not necessarily based on time.
>>>bill
>>
>>Hi Bill,
>>There was an article in Scientific American in approximately 1990-1991
>>which had a graph showing the play ratings of various chess programs and
>>how many plies deep they searched.  I don't have the article handy here;
>>I would have to dig it up.  But I do remember definitely that the graph
>>implied that a program's rating increased by 180-200 points for each ply
>>deeper it searched.
>>It was displayed as a straight-line graph.  I don't know if that's right
>>or wrong; it's certainly debatable.
>>-Jim Phillips
>
>Bill,
>I dug out that article when I got home and took a careful look at the
>graph.  It's linear all the way from beginner up to 2000+ rating....
>I assume it is for programs with a lot of knowledge, playing at 40/120
>time control.  I determined that a best-fit formula to duplicate the
>graph is:
>  U.S. Chess Federation Rating = (200 x Ply Depth) + 550
>This could be applied to your idea in your other post for a computer
>program that rates its human opponent.  I've had some other ideas about
>that since reading your post; if I come up with a general approach I'll
>post it.  Such a program would certainly be a worthwhile project... very
>interesting if nothing else....
>-Jim Phillips


It was common even in the old days for programs to have selective extensions.
(i.e. capture search.)  for example, the Novag Super Constellation was at
1 ply a lot stronger than 750.  It was more like 1300.  So the question
becomes are we talking about the maximum ply a program can look at?

john Coffey



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