Jirí Adámek; Lurdes Sousa;
On reflective subcategories of varieties
Full reflective subcategories of varieties are characterized as the cocomplete categories with a regular generator, or as classes of algebras presented by "preequations". As a byproduct, a solution is presented to the problem of describing omega-orthogonality classes of locally finitely presentable categories in terms of closure properties.
Journal of Algebra