For each horizontal morphism $R\colon A\mathrel {\rightarrow \kern -9.5pt\mathrlap {|}\kern 6pt}B$ of $\mathsf{Rel}^{\mathsf{dbl}}$, the component
- 1As proved in Item 3 of Proposition 8.1.3.1.4.
8.3.5.7 The Right Unitors
For each horizontal morphism $R\colon A\mathrel {\rightarrow \kern -9.5pt\mathrlap {|}\kern 6pt}B$ of $\mathsf{Rel}^{\mathsf{dbl}}$, the component
