Could the front page 'merit' be more or less ~accurately~ described via continuous function?
for (User user : item.up_voters) merit += user.life_span_in_months/12;
for (User user : item.down_voters) merit -= user.life_span_in_months/12;
Taking the interest forumula "Pe^(tr)", and substituting might yield something like:
P = 1, -1, it is the single up/down vote
t = user life span in years
r = karma/submissions (karma_density)
for (user:item.voters) item.merit += (sign_of_vote)e^((user.life_span/12)(user.karma/user.submissions))