Six functor formalisms via internal higher algebra

Abstract

We extend a six-functor formalism $D:\mathrm{Span}(C,E)\to \mathrm{Cat}$ to a lax symmetric monoidal functor of $(\infty ,2)$-categories ${\mathbf{Span}}^2(C,E{)}_I^P\to \mathbf{Cat}$, where $P$ and $I$ are the classes of $D$-proper and $D$-étale morphisms, respectively. This proves a conjecture of Mann and generalizes a special case of a theorem of Cnossen, Lenz, and Linskens. To prove this result, we develop a theory of internal $\mathsf{E}$-monoidal categories and $\mathsf{E}$-operads, where $\mathsf{E}$ is a local class of morphisms in an $\infty$-topos. These notions generalize the internal symmetric monoidal categories and operads developed by Martini and Wolf.