On Polish spaces Lipschitz universal for separable metric spaces
On some applications of infinite-dimensional manifolds to the theory of shape
On some dense subspaces of topological linear spaces
On subcompactness and countable subcompactness of metrizable spaces in ZF
We show in ZF that: (i) Every subcompact metrizable space is completely metrizable, and every completely metrizable space is countably subcompact. (ii) A metrizable space is countably compact if and only if it is countably subcompact relative to . (iii) For every metrizable space , the following are equivalent: (a) is compact; (b) for every open filter of , ; (c) is subcompact relative to . We also show: (iv) The negation of each of the statements, (a) every countably subcompact metrizable...
On the convergence of certain sequences and some applications
On the differentiation theorem in metric groups
On the generalized property
On the structure of the dual complexity space: The general case.
Partitioning spaces into homeomorphic rigid parts
Perfect pre-images of cofinally complete metric spaces
We show that a Tychonoff space is the perfect pre-image of a cofinally complete metric space if and only if it is paracompact and cofinally Čech complete. Further properties of these spaces are discussed. In particular, cofinal Čech completeness is preserved both by perfect mappings and by continuous open mappings.
Polishness of weak topologies generated by gap and excess functionals.
Properties of one-point completions of a noncompact metrizable space
If a metrizable space is dense in a metrizable space , then is called a metric extension of . If and are metric extensions of and there is a continuous map of into keeping pointwise fixed, we write . If is noncompact and metrizable, then denotes the set of metric extensions of , where and are identified if and , i.e., if there is a homeomorphism of onto keeping pointwise fixed. is a large complicated poset studied extensively by V. Bel’nov [The structure of...
Recent developments in the theory of Borel reducibility
Let E₀ be the Vitali equivalence relation and E₃ the product of countably many copies of E₀. Two new dichotomy theorems for Borel equivalence relations are proved. First, for any Borel equivalence relation E that is (Borel) reducible to E₃, either E is reducible to E₀ or else E₃ is reducible to E. Second, if E is a Borel equivalence relation induced by a Borel action of a closed subgroup of the infinite symmetric group that admits an invariant metric, then either E is reducible to a countable...
Remarks on coupled fixed point theorem in cone metric spaces
Representations of commutative semigroups by products of metric -dimensional spaces
Selection theorems for partitions of Polish spaces
Selections that characterize topological completeness
We show that the assertions of some fundamental selection theorems for lower-semicontinuous maps with completely metrizable range and metrizable domain actually characterize topological completeness of the target space. We also show that certain natural restrictions on the class of the domains change this situation. The results provide in particular answers to questions asked by Engelking, Heath and Michael [3] and Gutev, Nedev, Pelant and Valov [5].
Selections using orderings (non-separable case)
Sequentially complete spaces
Set-valued mappings on metric spaces