Monoidal category action

In algebra, an action of a monoidal category S on a category X is a functor

$\cdot: S \times X \to X$

such that there are natural isomorphisms $s \cdot (t \cdot x) \simeq (s \cdot t)\cdot x$ and $e \cdot x \simeq x$ and those natural isomorphism satisfy the coherence conditions analogous to those in S. If there is such an action, S is said to act on X.

For example, S acts on itself via the monoid operation ⊗.

References

• C. Weibel "The K-book: An introduction to algebraic K-theory"