 Every partially ordered set can be viewed as a category (where the elements of the poset become the category's objects and we have a single morphism from "x" to "y" if and only if "x" ≤ "y").A pair of adjoint functors between two partially ordered sets is called a Galois connection (or, if it is contravariant, an "antitone" Galois connection).See that article for a number of examples