April Fools! Your rating has been reset to zero!

If you've been paying attention to the discussion on the DMOJ Discord recently, you may have been aware that there has been some discontent with new users being able to get Grandmaster rating after participating in a single contest with a rating ceiling intended for Candidate Master / Master rated users. In response, we've been working on overhauling the rating system, with a particular focus on contests with rating ceilings. At a very high level, ratings should not exceed 400 plus the rating ceiling (naturally, this is unbounded for contests with no rating ceilings).

All users have had their ratings retroactively changed as if DMOJ had always been using this new system. Furthermore, "rating gain caps" were added to contests labelled as "Junior" contests. (More technically, they had performance_ceiling set to 2000). Finally, rating ceilings have been retroactively removed from all previous contests (as these would no longer make sense with the new ratings). Any users who were originally not rated have been manually excluded from ratings.

The changes in rating are as follows:

For further explanation, including technical details, we recommend checking out the implementation on GitHub, the original Elo-MMR paper, and this brief discussion with the Elo-MMR creator regarding how to handle contests with rating ceilings.

Finally, please reach out, either via the comments section, via email at contact -at- dmoj -dot- ca, via the issue tracker on Github, or via the Discord if you have any concerns, or wish to report any issues.