"Every few minutes, a line with the current value for S(h, t) is emitted."
Hard to believe the author didn't notice this...
Maybe just some humor for the trending classification overview?
Anyone who knows where to learn more about the system design they use, with the pre-processor, parser, scorer, and ranker?
How do these interact? What's the respective input and output?
Links to some similar system with more in-depth on this area would be appreciated.
Interesting that most hashtags don't get more than 3 posts per hour - that breakdown would be a good graph to see! It's also curious that they don't apply some type of seasonal decomposition to the timeseries data; though perhaps that that makes sense with Instagram's particular data.
[1]http://mashable.com/2010/05/14/twitter-improves-trending-top...
Also, I found a typo:
> ... to requests comping from the app
(I think that should be 'coming from the app')