Editing Adjoint functors (section)

===Universal constructions===

As stated earlier, an adjunction between categories ''C'' and ''D'' gives rise to a family of [[universal morphism]]s, one for each object in ''C'' and one for each object in ''D''. Conversely, if there exists a universal morphism to a functor ''G'' : ''C'' → ''D'' from every object of ''D'', then ''G'' has a left adjoint.

However, universal constructions are more general than adjoint functors: a universal construction is like an optimization problem; it gives rise to an adjoint pair if and only if this problem has a solution for every object of ''D'' (equivalently, every object of ''C'').