The OGS site is lacking an exact calculation of the rank.
I only find this explanation in the help:
which only refer to wikipedia. However the wikipedia page is a simple generic formula.
But when investigating why my rank has decreased after a win just today (2020-05-03 dhpmrou win against jacob.harison09 who had a temporary rank, my rank dropped from 11.7k to 11.6k in 15’), I found scattered information in the forum, like the rank is computed from the last 15 matches (or one month if less), that the rank is recomputed from the current rank of past opponent (it seems). Plus there is an allusion at a change of calculation of the rank end 2018 (?), so it is not quite clear when reading a post whether this information is obsolete or not.
It would be very nice to have an uptodate, complete, technically accurate description on how the rank is actually computed.
Btw, I believe the most common reason a rank can decrease after a victory is simply because the opponent rank is worse than the one of the opponent of a victory 15 games in the past which is not taken into account any more. Well if the rank calculation technique I pieced together is the correct one.
Thank you for your attention.