Thanks. Will look into it. If it can do two levels, why not three or more? Sounds as if there’s just a variable that needs to be changed from 2 to n. Or is there, I’m wondering, anything fundamentally different between n and 2?

Currently, topic categories are used to label the generated topics, hence the single additional level.

Expanding functionality to include something like this is possible though. The community detection algorithms kind of do this in a way. Each iteration builds smaller and smaller communities.