On the Whitehead Theorem in shape theory
On the -continuous fixed point property.
On the -primitive
On theorems of Pu & Pu and Grande
Given a finite family of cliquish functions, , we can find a Lebesgue function such that is Darboux and quasi-continuous for every . This theorem is a generalization both of the theorem by H. W. Pu H. H. Pu and of the theorem by Z. Grande.
On topological and algebraic structure of extremally disconnected semitopological groups
Starting with a very simple proof of Frol’ık’s theorem on homeomorphisms of extremally disconnected spaces, we show how this theorem implies a well known result of Malychin: that every extremally disconnected topological group contains an open and closed subgroup, consisting of elements of order . We also apply Frol’ık’s theorem to obtain some further theorems on the structure of extremally disconnected topological groups and of semitopological groups with continuous inverse. In particular, every...
On topological factors of 3 dimensional locally connected continuum embeddable in
On topological groups with a small base and metrizability
A (Hausdorff) topological group is said to have a -base if it admits a base of neighbourhoods of the unit, , such that whenever β ≤ α for all . The class of all metrizable topological groups is a proper subclass of the class of all topological groups having a -base. We prove that a topological group is metrizable iff it is Fréchet-Urysohn and has a -base. We also show that any precompact set in a topological group is metrizable, and hence G is strictly angelic. We deduce from this result...
On topological properties of the spaces of Darboux Baire 1 functions and bounded derivatives
We investigate the topological structure of the space 𝓓ℬ₁ of bounded Darboux Baire 1 functions on [0,1] with the metric of uniform convergence and with the p*-topology. We also investigate some properties of the set Δ of bounded derivatives.
On Topological Spaces With Dense Completely Metrizable Subspaces
On transfinite convergence and generalized continuity
On transfinite dimension
On transfinite sequences of mappings
On transformations of sets in
On trivially semi-metrizable and D-completely regular mappings
Trivially symmetrizable, trivially semi-metrizable and trivially D-completely regular mappings are defined. They are characterized as mappings parallel to symmetrizable, semi-metrizable and D-completely regular spaces correspondently. One shows that trivially D-completely regular mappings, i.e. submappings of fibrewise products of developable mappings coincide (up to homeomorphisms) with submappings of fibrewise products of semi-metrizable mappings.
On two questions of the theory of retracts.
On two theorems of Dyer
On typical parametrizations of finite-dimensional compacta on the Cantor set
We prove that if X is a perfect finite-dimensional compactum, then for almost every continuous surjection of the Cantor set onto X, the set of points of maximal order is uncountable. Moreover, if X is a perfect compactum of positive finite dimension then for a typical parametrization of X on the Cantor set, the set of points of maximal order is homeomorphic to the product of the rationals and the Cantor set.
On unified theory for continuities.
On uniform approximation of bounded approximately continuous functions by differences of lower semicontinuous and approximately continuous ones
On uniform spaces