Hereditary coreflective subcategories of an epireflective
subcategory A of Top such that A2ÍA (here
A2 is the 2-point indiscrete space) were studied in [C].
It was shown that a coreflective subcategory B of
A is
hereditary (closed under the formation of subspaces)
if and only if it is
closed under the formation of prime factors. The main problem
studied in this paper is the question whether this claim remains
true if we study the (more general) subcategories of A which
are closed under topological sums and quotients in A instead
of the coreflective subcategories of A.
We show that this is true if
AÍHaus
or under some
reasonable conditions on B.
E.g., this holds if B
contains either a prime space, or a space which is not locally connected,
or a totally disconnected space or a non-discrete Hausdorff space.
We touch also other questions related to such subclasses of A. We introduce a method extending the results from the case of
non-bireflective subcategories (which was studied in
[C]) to arbitrary epireflective subcategories of Top.
We also prove some new facts about the lattice of coreflective
subcategories of Top and ZD.
[C] J. Činčura: Heredity and coreflective subcategories of the category of topological spaces. Appl. Categ. Structures 9, 131–138 (2001)