 Dinatural transformation

A dinatural transformation is a concept in category theory, specifically in the context of functors and natural transformations. It generalizes the notion of a natural transformation to situations involving two different functors that are indexed by a third category. In more detail, consider two categories \( \mathcal{C} \) and \( \mathcal{D} \), along with a third category \( \mathcal{E} \).