[amatsukawa]

No, I believe he actually meant LSA = latent semantic analysis, which is an algorithm used to extract topics.

I am also curious about how the NLP/ML parts are implemented, as it's claimed by the README on github. Briefly scanned the code but didn't really spot it.

[MojoJolo]

It's more of statistical NLP and a bit of machine learning. The algorithm can be found here: https://github.com/MojoJolo/textteaser/blob/master/src/main/...