See http://news.ycombinator.com/item?id=1162965<p>pg's comment, with just 17 points, is placed above brh's comment, which has 110 points. Both the comments are from 262 days ago.<p>Why is this so?
Looking at the arc 3.1 source, I'm not sure why that's the case.<p>The real work here is done by * frontpage-rank* . It's implemented as follows:<p><pre><code> (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)) .5
(blank s!url) nourl-factor*
(lightweight s) (min lightweight-factor*
(contro-factor s))
(contro-factor s))))
</code></pre>
<i>realscore</i> subtracts any votes that are noted as "sockvotes" from the item's raw score.<p>The first few lines here won't change too much here for either comment. Obviously, the 110 point comment will have a higher base score than the 17 point comment. They're about the same age, so (expt (/ (+ (item-age s) timebase* ) 60) gravity) will be about the same for each of them. So the division will come up with a number that's a few times higher for brh's comment.<p>The interesting part is the multiplication here. I don't think either would be considered a story, so neither is being multiplied by .5; neither has a blank url, so they're not getting hit by nourl-factor<i>.<p>It comes down to the final part, whether one is considered "lightweight", and what the </i>contro-factor* of each is. It takes into account the number of children of the comment (the <i>visible-family</i> call). It shouldn't make a difference, though -- neither of the posts has more than 20 children, so contro-factor for both should be 1. I think I'm missing something, as what I've said wouldn't explain the ordering.<p>Notably, though, it doesn't take into either account karma or average karma of the poster to determine rank.<p>Edit: as ChaosMachine pointed out, it does take into account users' average karma: <a href="http://news.ycombinator.com/item?id=1923716" rel="nofollow">http://news.ycombinator.com/item?id=1923716</a> . Ey pointed out that pg's post is here: <a href="http://news.ycombinator.com/item?id=1398764" rel="nofollow">http://news.ycombinator.com/item?id=1398764</a>
Possibly still due to the time decay function. I don't know exactly when each comment was created, but pg's comment may have been more recent (within 24 hours). I haven't looked at the inner workings, but I imagine that upvotes might also be weighted more for how recent they are. Example: pg's comment may have received 17 upvotes within a minute of posting, and his post was 4 hours after brh's, and brh's upvotes happened slower, or before pg's comment.<p>This is all speculation. Maybe someone who has looked at the code could confirm or debunk this.
Note that pg can do whatever he wants in the REPL.<p>I haven't noticed any thread ordering tomfoolery before, but he's definitely hidden posts from the index pages before without [dead]-ing them.
More comments on pg's thread.<p>As an experiment; let's upvote chaosmachines comment to 5 add 1 comment, leave mine get mine to 3 & add 3 comments.