Alas, Ofelia T.; Madriz-Mendoza, Maira; Wilson, Richard G.(Universitat Politècnica de València, 2012-04-01)
[EN] We prove some cardinal inequalities valid in the classes of Whyburn and hereditarily weakly Whyburn spaces and we construct examples of non-Whyburn and non-weakly Whyburn spaces to illustrate that some previously known ...
Fernández, Manuel; Tkachenko, Mikhail G.(Editorial Universitat Politècnica de València, 2014-10-01)
[EN] It is shown that if all countable subgroups of a semitopological group G are precompact, then G is also precompact and that the closure of an arbitrary subgroup of G is again a subgroup. We present a general method ...