Terminal coalgebras via modules


Venue   88th Peripatetic Seminar on Sheaves and Logic, University of Cambridge, 5 April 2009.

Summary   This was a joint talk with Apostolos Matzaris. I gave the first half, and he gave the second.

In my half, I explained a new proof (and all the terminology) of the following old theorem:

    Every finitary endofunctor of a locally finitely presentable category has a terminal coalgebra.

The new proof not only proves existence; it actually constructs the terminal coalgebra. It is due to Panagis Karazeris, Apostolos Matzaris, and Jiří Velebil, building on some work of my own on self-similarity.

Slides   First half (me); second half (Apostolos).

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