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How does Lemmy decide what goes in the hot feed?
(lemmy.world)
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this post was submitted on 18 Jul 2023
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After all of this, I will amend my response to say that I think that there must be something going wrong with the algorithm. Consider these two consecutive posts on my "hot" feed:
The anti-vax nonsense from two years ago was appropriately downvoted to hell. The post right underneath it is one year old and has a post score of +13. Based on the equation above, the lower post must have a higher rank than the anti-vax post, as it should have both a higher numerator and a lower denominator.
Time for a review of the source code? Or am I missing something? Do other people see this phenomenon? No older, lower-scored post should be above a newer and higher-scored post in your feed, I think.
After a year, both have basically the same rank = 0
8765 hours in a year, growing exponentially, while the score is static and growns in log.
Yeah - though I had thought that still the one should be higher than the other, even if the numbers are small. In the actual equation, this would be multiplied by a scaling factor of 10000, though. (See the code discussion in the other comments). Though, in this case, the rank would still be very close to zero.
What I had missed is that, in the actual code, the equation is wrapped in
floor()and returns an integer. So both are treated as rank = 0 and maybe randomly sorted.The question is why are rank 0 posts showing up at all? In my other comment, if you do the math, I think that it should take quite a bit of time for any post with an appreciable score to decay to a rank of zero. Yet we see that these sorts of old posts are appearing relatively high in the hot feed.
One possible answer was suggested in another comment -- it may have to do with how often the scores are recalculated for older posts, and if some have not decayed to zero by the time that the score recalculation stops, they might persist with a non zero score until the instance is restarted. I'm still not sure that that is the right answer, however, because I am guessing that instances like lemmy.world (which I am using) have been restarted recently with the various hacking attempts?
Didn't knew the value of the scaling factor, but supposed it didn't mattered a lot when the denominator of the division is in the 10^(-8) range.
Another problem in my opinion is in the log(max(1,3+score)), anything with a score of -2 or less send the max function to 1, the log(1) to 0 and the whole score to 0, so the distributions of post with score 0 should be gigantic without discrimination of a controversial - something score post against something with a score of - thousands. Also, some malicious agent can just use 3 bots to totally fuck all the post on new.