Rétractions, corétractions et enveloppe injective dʹune algèbre de transitions Original Research Article

The notions of retraction and injectivity have been useful in the study of many categories (category of modules over a ring, category of posets, category of metric spaces over an Heyting albegra ...). In this article the category of Σ-transition algebras is considered, and in this frame, answers are given to the key questions related to these notions. F