RÉSUMÉ. Cet article étudie l’enveloppe réflective engendrée par une sous-catégorie pleine d’une catégorie complète. Il s’agit de la plus petite sous-catégorie qui est pleine et réflective. Comme application nous obtenons l’enveloppe coréflective de la sous-catégorie pleine de cubes pointés dans la catégorie des espaces topologiques pointés. Par la suite nous déterminons l’enveloppe réflective d...

We provide a fairly general method, which is straightforward and widely applicable, for constructing some coreflections in the category of nearness frames. The method captures all coreflective subcategories with 1 1 coreflection maps; this includes the well-known uniform, totally bounded and separable coreflections. The primary application of this method answers in the affirmative the question ...

Several methods for constructing left determined model structures are expounded. The starting point is Olschok’s work on locally presentable categories. We give sufficient conditions to obtain left determined model structures on a full reflective subcategory, on a full coreflective subcategory and on a comma category. An application is given by constructing a left determined model structure on ...

We characterize abstract Morita contexts in several bicategories. In particular, we use heteromorphisms for the bicategory Prof of categories and profunctors and coreflective subcategories for Cat (categories and functors). In addition, we prove general statements concerning strict Morita contexts, and we give new equivalent forms to the standard notions of adjointness, category equivalence and...