On symmetric products
On Telgársky's question concerning β-favorability of the strong Choquet game
Answering a question of Telgársky in the negative, it is shown that there is a space which is β-favorable in the strong Choquet game, but all of its nonempty -subspaces are of the second category in themselves.
On the 2-homogeneity of Cartesian products
On the cardinality of power homogeneous Hausdorff spaces
We prove that the cardinality of power homogeneous Hausdorff spaces X is bounded by . This inequality improves many known results and it also solves a question by J. van Mill. We further introduce Δ-power homogeneity, which leads to a new proof of van Douwen’s theorem.
On the category of topological topologies
On the class of all spaces of weight not greater than ω_1 whose Cartesian product with every Lindelöf space is Lindelöf
On the co-completeness of the category of Hausdorff uniform spaces.
On the Compactness and Countable Compactness of in ZF
In the framework of ZF (Zermelo-Fraenkel set theory without the Axiom of Choice) we provide topological and Boolean-algebraic characterizations of the statements " is countably compact" and " is compact"
On the construction of the extensional topological hull
On the deficiency of product spaces
On the density of the hyperspace of a metric space
We calculate the density of the hyperspace of a metric space, endowed with the Hausdorff or the locally finite topology. To this end, we introduce suitable generalizations of the notions of totally bounded and compact metric space.
On the division by Rn.
On the embedding theorem
On the exact completion of the homotopy category
On the existence of maps having graphs connected and dense
On the External Characterization of Topological Functors.
On the foundations of Topology
On the functor of order-preserving functionals
We introduce a functor of order-preserving functionals which contains some known functors as subfunctors. It is shown that this functor is weakly normal and generates a monad.
On the fundamental dimension of the Cartesian product of compacta with the fundamental dimension 2
On the Hausdorff Dimension of Topological Subspaces
It is shown that every Polish space X with admits a compact subspace Y such that where and denote the topological and Hausdorff dimensions, respectively.