Extranatural transformation

In mathematics, specifically in category theory, an extranatural transformation is a generalization of the notion of natural transformation. == Definition == Let F : A × B o p × B → D {\displaystyle F:A\times B^{\mathrm {op} }\times B\rightarrow D} and G : A × C o p × C → D {\displaystyle G:A\times C^{\mathrm {op} }\times C\rightarrow D} be two functors of categories.