Comment by antirez

When I built oknotizie.virgilio.it many years ago, more or less at the same time reddit was created, I used the same base algorithm, that is: RANK = SCORE / AGE^ALPHA, where ALPHA is the obsolescence factor.

This is a pretty obvious algorithm, but the evil is in the details. First, since oknotizie is based in italy AGE is calculated in a special way so that nightly hours are calculated in a different way (every hour should be take into account proportionally to the traffic that there is in this hour).

Second, there is to do a lot of filtering. Oknotizie is completely built out of anti-spamming: statistical analysis on users voting patterns, cycles detection, an algorithm penalizing similarities in general in the home page, and so forth.

To run a simple HN style site is simple as long as the community is not trying hard to game it. Otherwise it starts to get a much more complex (and sad) affair.