On -distance in three dimensional space.
On -images of metric spaces.
On -metrizable spaces, their continuous images and products
A space is said to be -metrizable if it has a -discrete -base. The behavior of -metrizable spaces under certain types of mappings is studied. In particular we characterize strongly -separable spaces as those which are the image of a -metrizable space under a perfect mapping. Each Tychonoff space can be represented as the image of a -metrizable space under an open continuous mapping. A question posed by Arhangel’skii regarding if a -metrizable topological group must be metrizable receives...
On --images of metric spaces.
On -discrete Borel mappings via quasi-metrics
On -discreteness in uniform spaces
Only 3-generalized metric spaces have a compatible symmetric topology
We prove that every 3-generalized metric space is metrizable. We also show that for any ʋ with ʋ ≥ 4, not every ʋ-generalized metric space has a compatible symmetric topology.
Open cover of a metric space admits -partition of unity
Ordered spaces with special bases
We study the roles played by four special types of bases (weakly uniform bases, ω-in-ω bases, open-in-finite bases, and sharp bases) in the classes of linearly ordered and generalized ordered spaces. For example, we show that a generalized ordered space has a weakly uniform base if and only if it is quasi-developable and has a -diagonal, that a linearly ordered space has a point-countable base if and only if it is first-countable and has an ω-in-ω base, and that metrizability in a generalized ordered...
Ordinary and directed combinatorial homotopy, applied to image analysis and concurrency.
-embeddings, AR and ANR spaces.
Pairwise monotonically normal spaces.
Pairwise monotonically normal spaces
We introduce and study the notion of pairwise monotonically normal space as a bitopological extension of the monotonically normal spaces of Heath, Lutzer and Zenor. In particular, we characterize those spaces by using a mixed condition of insertion and extension of real-valued functions. This result generalizes, at the same time improves, a well-known theorem of Heath, Lutzer and Zenor. We also obtain some solutions to the quasi-metrization problem in terms of the pairwise monotone normality.
Paratopological (topological) groups with certain networks
In this paper, we discuss certain networks on paratopological (or topological) groups and give positive or negative answers to the questions in [Lin2013]. We also prove that a non-locally compact, -gentle paratopological group is metrizable if its remainder (in the Hausdorff compactification) is a Fréchet-Urysohn space with a point-countable cs*-network, which improves some theorems in [Liu C., Metrizability of paratopological semitopological groups, Topology Appl. 159 (2012), 1415–1420], [Liu...
Peano compactifications and property S metric spaces.
Perfectness of the Higson and Smirnov compactifications
We provide a necessary and sufficient condition for the Higson compactification to be perfect for the noncompact, locally connected, proper metric spaces. We also discuss perfectness of the Smirnov compactification.
Positive definite functions and coincidences
Precompactness and total boundedness in products of metric spaces.
Prescribed ultrametrics
Products of non--lower porous sets
In the present article we provide an example of two closed non--lower porous sets such that the product is lower porous. On the other hand, we prove the following: Let and be topologically complete metric spaces, let be a non--lower porous Suslin set and let be a non--porous Suslin set. Then the product is non--lower porous. We also provide a brief summary of some basic properties of lower porosity, including a simple characterization of Suslin non--lower porous sets in topologically...