Cancellative actions
The following problem is considered: when can the action of a cancellative semigroup on a set be extended to a simply transitive action of the universal group of on a larger set.
Catégories cartésiennement fermées engendrées par des monoïdes
Categorified algebra and quantum mechanics.
Central extensions and reciprocity laws
Colimits in free categories
Commutative semigroup cohomology.
Congruences on ordered groupoids.
Constructing ordered groupoids
Construction of all homomorphisms of groupoids
Crossed modules as -categories
Crossed semimodules and Schreier internal categories in the category of monoids.