On algebraic models for homotopy 3-types.
On cohomology of graded group categories
On Galois -objects and invertible -modules
On reflexive subobject lattices and reflexive endomorphism algebras
In this paper we study the reflexive subobject lattices and reflexive endomorphism algebras in a concrete category. For the category Set of sets and mappings, a complete characterization for both reflexive subobject lattices and reflexive endomorphism algebras is obtained. Some partial results are also proved for the category of abelian groups.
On the axiomatisation of Boolean categories with and without medial.
On the braiding on a Hopf algebra in a braided category.
On the completeness of localic groups
The main purpose of this paper is to show that any localic group is complete in its two-sided uniformity, settling a problem open since work began in this area a decade ago. In addition, a number of other results are established, providing in particular a new functor from topological to localic groups and an alternative characterization of -groups.
On the representability of actions in a semi-abelian category.