All in all, it's actively curated by PG, with small changes to keep the system in balance and running smoothly. Enquiring too closely is discouraged.
It's also plausible that this item will get deleted. After all, this is a site for hackers, not a site about Hacker News.
I understand that there's always more chance that if its fully disclosed, it might be used to game the system.. but could stop my curiousity, hence the question :).
quoting from PG's comment on that post:
(= gravity* 1.8 timebase* 120 front-threshold* 1 nourl-factor* .4 lightweight-factor* .17 gag-factor* .1)
(def frontpage-rank (s (o scorefn realscore) (o gravity gravity*))
(* (/ (let base (- (scorefn s) 1)
(if (> base 0) (expt base .8) base))
(expt (/ (+ (item-age s) timebase*) 60) gravity))
(if (no (in s!type 'story 'poll)) .8
(blank s!url) nourl-factor*
(mem 'bury s!keys) .001
(* (contro-factor s)
(if (mem 'gag s!keys)
gag-factor*
(lightweight s)
lightweight-factor*
1)))))or simplifying a bit:
Score = (P-1) / (T+2)^G
where, P = points of an item (and -1 is to negate submitters vote) T = time since submission (in hours) G = Gravity, defaults to 1.8 in news.arc
the question was something like this... how come a 20 upvote link gets displayed higher than a 40 upvote link when both are carrying similar timestamps?