Author: John Merlino
Date: 09:37:28 10/08/02
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On October 08, 2002 at 12:20:19, Brian Thomas wrote: >I noticed that while playing against the computer in CM9000, I'm playing about >200 or so points higher in 9000 than I was in 8000. (To clarify, in playing 10 >minute games I'd typically play a 1500 for a casual game, now I'm playing around >1700 at the same level in 9000). While I'd like to think this is due to playing >better, I'm guessing the ratings or playing style has been adjusted in this >version. John, is this true? Can you provide specifics about what was tweaked? > >thanks! >Brian There were two ratings calculation "tweaks", one in the upward direction and one in the downward direction. The upward one involved raising the base rating of all personalities by about 30-50 points, based on what Johan believed was the minimum strength increase of the new engine. The downward one involved re-evaluating the function that added a certain amount of points to a rating based on the speed of a user's CPU. Back in CM7000, we added 70 points for each doubling of CPU speed above the minimum spec machine. That was eventually lowered to 50 points, and I think it is now at 30-40 points, due to diminishing returns. So, some personalities will have lower ratings because they are more affected by the downward tweak (this is usually the higher-rated personalities, like CM and the GMs). And other personalities will have higher ratings because they are more affected by the upward tweak (the lower-rated personalities, or the ones that have a limited search depth and do not get a bonus for fast CPUs). However, the BIGGEST change was not really a tweak at all. Many personalities were actually SWAPPED with other personalities. In other words, we swapped faces and bios with personality settings, almost always in the downward direction. The most obvious example is the Liam personality. It was rated in the 2550-2600 range in CM8000, but is now only in the 1750-1800 range! I don't have a list of the personalities that were affected by this, but it is easy to compare if you have both programs. jm
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