Distributive lattices with finite projective covers
Alan Day, Herbert S. Gaskill, Werner Poguntke · Pacific Journal of Mathematics · 1979
A projective cover in a category, J%Γ, of algebras is a morphism φ\P-> A where A, Pe-%^, P is projective in JfΓ and no proper subalgebra of P has A as its direct image under φ.Projective covers of finite distributive lattices in the categories *£?, of all lattices and -S^πn of all finite lattices are determined (when they exist).