All Concepts are $\mathbb{C}{\mathbf{at}}^{\#}$

Owen Lynch, Brandon T. Shapiro, David I. Spivak

We show that the double category $\mathbb{C}{\mathbf{at}}^{\#}$ of comonoids in the category of polynomial functors (previously shown by Ahman-Uustalu and Garner to be equivalent to th…