On local isometries and isometries in metric spaces
On locally expansive selfcoverings of compact metrizable spaces
On medial properties of maps
On pairs of compacta with dim(X×Y) < dimX + dimY
On shapes of topological spaces
On spaces which have the shape of C. W. complexes
On spaces which have the shape of compact metric 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 classification of locally compact separable metric spaces
On the fundamental dimension of the Cartesian product of compacta with the fundamental dimension 2
On the metric reflection of a pseudometric space in ZF
We show: (i) The countable axiom of choice is equivalent to each one of the statements: (a) a pseudometric space is sequentially compact iff its metric reflection is sequentially compact, (b) a pseudometric space is complete iff its metric reflection is complete. (ii) The countable multiple choice axiom is equivalent to the statement: (a) a pseudometric space is Weierstrass-compact iff its metric reflection is Weierstrass-compact. (iii) The axiom of choice is equivalent to each one of the...
On transfinite inductive compactness degree
On universal infinite-dimensional spaces
Ordinal products of topological spaces
The notion of the ordinal product of a transfinite sequence of topological spaces which is an extension of the finite product operation is introduced. The dimensions of finite and infinite ordinal products are estimated. In particular, the dimensions of ordinary products of Smirnov's [S] and Henderson's [He1] compacta are calculated.
Planar rational compacta and universality
We prove that in some families of planar rational compacta there are no universal elements.
Projective potencies and multiplicative extension operators
Proper shape retracts
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...
Quasi-equivalence of compacta and spaces of components.
Let X, Y be two compacta with Sh(X) = Sh (Y). Then, the spaces of components of X, Y are homeomorphic. This does not happen, in general, when X, Y are quasi-equivalent. In this paper we give a sufficient condition for the existence of a homeomorphism between the spaces of components of two quasi-equivalent compacta X, Y which maps each component in a quasi-equivalent component.
Quasi-metrization and hereditary normality of compact bitopological spaces