Profunctor Algebra

Let P : 𝒟 op × 𝒟 Sets : 𝑃 superscript 𝒟 op 𝒟 Sets P:\mathcal{D}^{\mathrm{op}}\times\mathcal{D}\to\mathrm{Sets} be a Profunctor. A P 𝑃 P -algebra consists of a functor F : 𝒞 𝒟 : 𝐹 𝒞 𝒟 F:\mathcal{C}\to\mathcal{D} and an Extranatural Transformation α : P ( F ( ) , F ( = ) ) \alpha:\star\to P(F(-),F(=)) .

If 𝒞 𝒞 \mathcal{C} is the Terminal Category, then this reduces to a section α : P ( X , X ) : 𝛼 𝑃 𝑋 𝑋 \alpha:P(X,X) . Moreover, if P = 𝒟 ( F ( ) , G ( = ) ) 𝑃 𝒟 𝐹 𝐺 P=\mathcal{D}(F(-),G(=)) for some Functors F , G 𝐹 𝐺 F,G , then this further specializes to the definition of a Functor Dialgebra.