Let 𝒞 be a category of
Hausdorff topological groups. A Hausdorff topological group G is called a
B(𝒞) group if every continuous and almost open homomorphism from G
onto a group in 𝒞 is open. An internal characterization of such groups is
obtained. For certain 𝒞, the permanence properties of B(𝒞) groups and related
categories are investigated, with some positive results pertaining to products
and subobjects, and several counterexamples. Forms of the closed graph
theorem for topological groups are then obtained which generalize results of T.
Husain.