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They are talking about Latent Dirichlet Allocation which was made by Blei in 2002 ( http://en.wikipedia.org/wiki/Latent_Dirichlet_allocation )

Here is video by him where he explains the basic model as well timeline-related hacks the article talks about - http://video.google.com/videoplay?docid=3077213787166426672#

You can very easily play with LDA yourself with this toolkit - http://mallet.cs.umass.edu/

I think they're talking about this one:

This work uses the correlated topic model, which extends LDA to model correlations among the extracted topics.

Edit: and this one [pdf]:

Was I just looking at formulae or some pages taken from the Odyssey?

I guess we could get the computer to categorise it ...