Evan Patterson
I am an interdisciplinary researcher working at the interface of...
- Scientific and statistical modeling
- Category theory and categorical logic
- Software systems for the above
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From the blog
How to prove equations using diagrams, part 3: The setting of algebraic theories (10/14/2026)
In this third part of our series on equational reasoning using diagrams, we extend the logical setting from bare categories, corresponding to equational theories with only unary function symbols, to categories with finite products, corresponding to algebraic theories in the classical sense.
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Twisted double functors and loosely discrete opfibrations, 2026. Michael Lambert, David Jaz Myers, Evan Patterson.
We investigate notions of "loose module" or "loose copresheaf" over a double category: an action by the double category's loose morphisms. Two main models for loose copresheaves are introduced and compared, one based on twisted double functors—a new kind of double functor sending tight morphisms to loose morphisms and vice versa—and the other being loosely discrete opfibrations. We take the perspective that twisted copresheaves generalize indexed categories, putting the domain and codomain on an equal footing. Read more