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A selection theorem for set-valued maps into normally supercompact spaces
Authors: V. Valov
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Abstract
The following selection theorem is established:\\ Let $X$ be a compactum possessing a binary normal subbase $\mathcal S$ for its closed subsets. Then every set-valued $\mathcal S$-continuous map $\Phi\colon Z\to X$ with closed $\mathcal S$-convex values, where $Z$ is an arbitrary space, has a continuous single-valued selection. More generally, if $A\subset Z$ is closed and any map from $A$ to $X$ is continuously extendable to a map from $Z$ to $X$, then every selection for $\Phi|A$ can be extended to a selection for $\Phi$.\\ This theorem implies that if $X$ is a $\kappa$-metrizable (resp., $\kappa$-metrizable and connected) compactum with a normal binary closed subbase $\mathcal S$, then every open $\mathcal S$-convex surjection $f\colon X\to Y$ is a zero-soft (resp., soft) map. Our results provide some generalizations and specifications of Ivanov's results (see [5--7]) concerning superextensions of $\kappa$-metrizable compacta.Department of Computer Science and Mathematics
Nipissing University
100 College Drive, P.O. Box 5002
North Bay, ON, P1B 8L7
Canada
E-mail:
Nipissing University
100 College Drive, P.O. Box 5002
North Bay, ON, P1B 8L7
Canada
E-mail:
Fulltext
– 0.14 Mb
Contents
- Academician Mitrofan M. Choban founder of the moldavian scientific school in topology
- Liouville's theorem for vector-valued functions
- On the number of metrizable group topologies on countable groups
- Short signatures from the difficulty of factoring problem
- Selected Old Open Problems in General Topology
- Infinitely many maximal primitive positive clones in a diagonalizable algebra
- Functional compactifications of T0-spaces and bitopological structures
- On free groups in classes of groups with topologies
- On a four-dimensional hyperbolic manifold with finite volume
- On spaces of densely continuous forms
- A selection theorem for set-valued maps into normally supercompact spaces
- Minimal m-handle decomposition of three-dimensional handlebodies
- Examples of quasitopological groups
- Certain differential superordinations using a multiplier transformation and Ruscheweyh derivative
- The 20th Conference on Applied and Industrial Mathematics (CAIM-2012) dedicated to the 70th anniversary of Academician Mitrofan M. Choban
