Definition. Corecursive algebra
Fix an endofunctor . An algebra is corecursive when for every coalgebra there is exactly one hylomorphism from to . Equivalently, the functor of the hylomorphism profunctor is constantly a singleton. It is the dual of a recursive coalgebra: an -algebra in is corecursive exactly when it is recursive as an -coalgebra in .
Example. If is a terminal coalgebra, then is invertible and is a corecursive algebra: a solution of is the same thing as a solution of , that is, a coalgebra map into the terminal coalgebra, and there is exactly one, .