• Corpus ID: 2971491


  author={Hans-E. Porst},
It is shown that the categories of R-coalgebras for a commutative unital ring R and the category of A-corings for some R-algebra A as well as their respective categories of comodules are locally presentable. 

Fundamental Constructions for Coalgebras, Corings, and Comodules

  • H. Porst
  • Mathematics
    Appl. Categorical Struct.
  • 2008
The various categories of corings, coalgebras, and comodules are studied from a categorical perspective and new results concerning the existence of limits and of factorizations of morphisms are obtained.

Some Remarks on Localization in Coalgebras

We analyze the geometry of the Ext-quiver of a coalgebra C in order to study the behavior of simple and injective C-comodules under the action of the functors associated to a localizing subcategory

Comodules over semiperfect corings

We discuss when the Rat functor associated to a coring satisfying the left $\alpha$-condition is exact. We study the category of comodules over a semiperfect coring. We characterize semiperfect

Purity and homotopy theory of coalgebras

  • M. Stelzer
  • Mathematics
    Journal of Pure and Applied Algebra
  • 2019

Comonads and Galois Corings

We investigate which aspects of recent developments on Galois corings and comodules admit a formulation in terms of comonads. The general theory is applied to the study of Galois comodules over

Group Corings

Group corings are introduced, and functors between categories of comodules over group corings, and the relationship to graded modules over graded rings are studied, as well as Morita contexts associated to a group coring.


We introduce the category of bicomodules for a comonad in a Grothendieck category whose underlying functor is right exact and preserves direct sums. We char- acterize comonads with a separable

Corings over rings with local units

We show that the bicategory whose 0‐cells are corings over rings with local units is bi‐equivalent to the bicategory of comonads in (right) unital modules whose underlying functors are right exact

Frobenius functors for corings

We investigate Frobenius pairs between categories of comodules over rather general corings. We particularize to the case of the adjoint pair of functors associated to a morphism of corings over

Comatrix Corings an Invertible Bimodules

We extend Masuoka’s Theorem [11] concerning the isomorphism between the group of invertible bimodules in a non-commutative ring extension and the group of automorphisms of the associated Sweedler’s



Corings and Comodules

Preface Notations 1. Coalgebras and comodules 2. Bialgebras and hopf algebras 3. Corings and comodules 4. Corings and extensions of rings 5. Corings and entwining structures 6. Weak corings and

Hopf algebras : an introduction

Algebras and coalgebras comodules special classes of coalgebras bialgebras and Hopf algrebras integrals actions and coactions finite dimensional Hopf algebras the category theory language C-groups

On varieties and covarieties in a category

By dualising, the concept of coequation is arrived at such that covarieties, that is, coequationally specified classes of coalgebras with cofree objects, correspond precisely to comonadic categories.

Coalgebras over a commutative ring

Lehrbuch der Algebra

  • G. M.
  • Mathematics
  • 1896
A “Treatise on Algebra” is rarely found to fulfil the promise of its title. It is too often a mere collection of problems and examples, thrown together without much regard to order or method; such

Accessible categories : the foundations of categorical model theory

[F-S] D. Fremlin and S. Shelah, Pointwise compact and stable sets of measurable functions, manuscript, 1990. [G-G-M-S] N. Ghoussoub, G. Godefroy, B. Maurey, W. Schachermayer, Some topological and

On linear representations of affine groups. I

Germany E-mail: porst@math.uni-bremen

  • Germany E-mail: porst@math.uni-bremen