Galois correspondence for augmented monads

Abstract

We establish a Galois connection between sub-monads of an augmented monad and sub-functors of the forgetful functor from its Eilenberg-Moore category. This connection is given in terms of invariants and stabilizers defined through universal properties. An explicit procedure for the computation of invariants is given assuming the existence of suitable right adjoints. Additionally, in the context of monoidal closed categories, a characterization of stabilizers is made in terms of Tannakian reconstruction.