2 papers
math.CT2026
Doubly weak double categories
Aaron David Fairbanks, Michael Shulman
We propose a definition of double categories whose composition of 1-cells is weak in both directions. Namely, a doubly weak double category is a double computad -- a structure with…
math.CT2024
Strict universes for Grothendieck topoi
Daniel Gratzer, Michael Shulman, Jonathan Sterling
Hofmann and Streicher famously showed how to lift Grothendieck universes into presheaf topoi, and Streicher has extended their result to the case of sheaf topoi by sheafification.…