nLab
indexed adjoint functor theorem

Idea

The analog of the adjoint functor theorem for indexed categories.

Statement

Theorem

Let $𝒮$ be a cartesian category, let $ℂ$ and $𝔻$ be $𝒮$-indexed categories which are locally small and have all colimits, and suppose further that $ℂ$ is well-copowered? and has a separating family. Then an indexed functor $F:ℂ\to 𝔻$ has an indexed right adjoint precisely iff it is cocontinuous.

This is (Johnstone, theorem B2.4.6).

References

• R. Paré, D. Schumacher, Abstract families and the adjoint functor theorems, in Indexed categories and their applications, Lecture Notes in Math. vol 661 Springer (1978)

Section B2.4 in

• Peter Johnstone, Sketches of an Elephant