On the classes of dense and closed subobjects Original Research Article

We provide analogous characterizations of the families of dense and of closed subobjects with respect to closure operators. The analogous behavior of hereditary and minimal closure operators with respect to the families of dense and of closed subobjects respectively, is pointed out. We prove that, in the category of topological abelian groups, the total denseness cannot be described as denseness with respect to a closure operator.