On the lattice of f-subgroups

چکیده مقاله

In this paper we introduce the notions of f-subgroups and normal f-subgroups as natural generalizations of subgroups, normal subgroups and group topologies. It will be proved that the set of all f-subgroups on a group is a lattice containing the lattice of all normal f-subgroups as a sublattice. Some open questions are also presented.