They fall over time. The algorithm simply needs the date the item was created at and the amount of points.

The difference is that instead of doing the calculation from the "time since submission" (which changes over time and, as you say, won't work with Couch's views which can't emit values as time goes on) it does the calculation using the "created_at" property. In essence the outcome is the same.

Here's the algorithm I use which needs some better documentation :) https://github.com/lmatteis/hckr.it/blob/master/common/util....