On the lattice structure of topologies
On the Novák completion of convergence groups
On tightness in chain-net spaces
On weakly bisequential spaces
Weakly bisequential spaces were introduced by A.V. Arhangel'skii [1], in this paper. We discuss the relations between weakly bisequential spaces and metric spaces, countably bisequential spaces, Fréchet-Urysohn spaces.
On weak-open -images of metric spaces
In this paper, we give some characterizations of metric spaces under weak-open -mappings, which prove that a space is -developable (or Cauchy) if and only if it is a weak-open -image of a metric space.
On -images of separable metric spaces and a problem of Shou Lin
Open maps do not preserve Whyburn property
We show that a (weakly) Whyburn space may be mapped continuously via an open map onto a non (weakly) Whyburn space . This fact may happen even between topological groups and , a homomorphism, Whyburn and not even weakly Whyburn.
Ordinal invariants in topology II. Sequential order of compactifications
-sequential like properties in function spaces
We introduce the properties of a space to be strictly or strictly , where , and we analyze them and other generalizations of -sequentiality () in Function Spaces, such as Kombarov’s weakly and strongly -sequentiality, and Kocinac’s and -properties. We characterize these in in terms of cover-properties in ; and we prove that weak -sequentiality is equivalent to -property, where and , in the class of spaces which are -compact for every ; and that is a -space iff satisfies...
Productively Fréchet spaces
We solve the long standing problem of characterizing the class of strongly Fréchet spaces whose product with every strongly Fréchet space is also Fréchet.
Products of coarse convergence groups
Products of convergence properties
Products of -spaces, and questions
As is well-known, every product of a locally compact space with a -space is a -space. But, the product of a separable metric space with a -space need not be a -space. In this paper, we consider conditions for products to be -spaces, and pose some related questions.
Products of sequential convergence properties
Regularity and extension of mappings in sequential spaces
Remarks on discretely absolutely star-Lindelöf spaces
Semi-radiality in products.
Separation in sequential spaces under PMEA
Sequential Cauchy spaces
Sequential characterizations of metrizability