symmetric monoidal category

A monoidal category $𝒞$ with tensor product $\otimes$ is said to be symmetric if for every pair $A,B$ of objects in $𝒞$, there is an isomorphism

$$s_{AB}:A\otimes B\cong B\otimes A$$

that is natural in both $A$ and $B$ such that the following diagrams are commutative

1. (unit coherence for $s$):

   $$+=2cmA\otimes I$$