accessible monad




An accessible monad is a monad on an accessible category whose underlying functor is an accessible functor.


Category of algebras over an accessible monad


The Eilenberg-Moore category of a κ\kappa-accessible monad, def. , is a κ\kappa-accessible category. If in addition the category on which the monad acts is a κ\kappa-locally presentable category then so is the EM-category.

(Adamek-Rosicky, 2.78)

Moreover, let CC be a topos. Then

  • if a monad T:CCT : C \to C has a right adjoint then TAlg(C)=C TT Alg(C)= C^T is itself a topos;

  • if a comonad T:CCT : C \to C is left exact, then TCoAlg(C)=C TT CoAlg(C) = C_T is itself a topos.

See at topos of algebras over a monad for details.


Last revised on February 12, 2014 at 06:16:09. See the history of this page for a list of all contributions to it.