Searcharxiv⌕ Search

arXiv subjects

Elżbieta Pol

Publications and source records attributed to Elżbieta Pol.

5 recordsLinked to original sources

On closed embeddings in $P^N \cup Q^N$

We prove that if a separable metrizable $X$ is a union of two disjoint 0-dimensional sets $E$, $F$, $E$ is absolutely $G_δ$ and $F$ is absolutely $F_{σδ}$ then there is a closed embedding $h$ into the union of countable products of the irrationals and the rationals with $E$ being the preimage under $h$ of the countable product of the irrationals and $F$ being the preimage under $h$ of the countable product of the rationals. We prove also that for the set $H$ of points $x$ in the Hilbert cube such that for each $k$ there is $l$ with $x(2^k 3^l)=0$, whenever $A$ is an $F_{σδ}$ set in a compact one-dimensional space $X$, there is an embedding $h$ into the union of the countable product of the irrationals with added point $0$, and the countable product of the rationals, such that $A$ is the preimage under $h$ of the set $H$.

math.GN↗

On Closed Mappings of Sigma-Compact Spaces and Dimension

We prove that if K is a remainder of the Hilbert space (i.e., K is the complement of the Hilbert space in its metrizable compactification) then every non-one-point closed image of K either contains a compact set with no transfinite dimension or contains compact sets of arbitrarily high inductive transfinite dimension ind. We construct also for each natural n a sigma-compact metrizable n-dimensional space whose image under any non-constant closed map has dimension at least n, and analogous examples for the transfinite dimension ind.

math.GN↗

Isometric embeddings and continuous maps onto the irrationals

Let f be a continuous map of a complete separable metric space E onto the irrationals. We show that if a complete separable metric space M contains isometric copies of every closed relatively discrete set in E, then M contains also an isometric copy of some fiber of f. We shall show also that if all fibers of f have positive dimension, then the collection of closed zero-dimensional sets in E is non-analytic in the Wijsman hyperspace of E.

math.GN↗

The non-existence of common models for some classes of higher-dimensional hereditarily indecomposable continua

A continuum $K$ is a common model for the family ${\mathcal K}$ of continua if every member of ${\mathcal K}$ is a continuous image of $K$. We show that none of the following classes of spaces has a common model: 1) the class of strongly chaotic hereditarily indecomposable $n$-dimensional Cantor manifolds, for any given natural number $n$, 2) the class of strongly chaotic hereditarily indecomposable hereditarily strongly infinite-dimensional Cantor manifolds, 3) the class of strongly chaotic hereditarily indecomposable continua with transfinite dimension (small or large) equal to $α$, for any given ordinal number $α< ω_{1}$.

math.GN↗