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Subject: Re: A unique feature of CM8000

Author: John Merlino

Date: 15:53:18 02/22/01

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On February 22, 2001 at 18:32:30, Albert Silver wrote:

>I presume the numbers were conjured up by the marketing department. Of course >it would be easy to justify too: let's see, after 5 games, the program >performed at 2450 (on the P2), which means there is an error margin of... >about 200 points so we'll say it's rated "roughly" 2625 according to >tests... :-)
>
>                                     Albert

No conjuring at all.

The rating is an estimate based on several things:

1) The SSDF (an independent Swedish organization) rated the engine in the
previous version of Chessmaster to be approximately 2475 at tournament time
controls on a Pentium 90.

2) This rating was increased by approximately 150 points based on the minimum
spec machine for Chessmaster 8000, which is a Pentium II-233, under the general
rule that every doubling of processor speed increases rating by 70. So, it was
assumed that a PII-233 is about 4 times faster than a P-90 (although it is
probably more). So, now we're at approximately 2625.

3) The SSDF rating is FIDE, and the Chessmaster ratings are USCF, which adds
another 150 points (although, maybe it should only be 100 -- this is probably
the only suspect portion of the equation). So, now we're at approximately 2775.

4) Several thousand games were played between the computer personalities. In
some of them, the opponents were actual USCF rated humans, which gave the
results a much more "real-world" calculation. These games resulted in a
fine-tuning of Chessmaster's rating, but I'm not sure what the adjustment was
from that.
Overall, the Chessmaster personality scored +63 =1 -2 against 11 humans rated
above 2000 (average rating of these humans was 2145). I do know that the
strongest player in the test was rated 2375 and he lost all 6 games against the
Chessmaster. USCF ratings are believed to have this rule of thumb: If a player
is rated 400 or more points above his opponent, he is almost guaranteed to win
the game. So, this further enforces the 2775 rating from item 3.

5) A further adjustment is done based on your computer's speed.

jm



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