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On Finite-to-One Maps

  Published:2005-12-01
 Printed: Dec 2005
  • H. Murat Tuncali
  • Vesko Valov
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Abstract

Let $f\colon X\to Y$ be a $\sigma$-perfect $k$-dimensional surjective map of metrizable spaces such that $\dim Y\leq m$. It is shown that for every positive integer $p$ with $ p\leq m+k+1$ there exists a dense $G_{\delta}$-subset ${\mathcal H}(k,m,p)$ of $C(X,\uin^{k+p})$ with the source limitation topology such that each fiber of $f\triangle g$, $g\in{\mathcal H}(k,m,p)$, contains at most $\max\{k+m-p+2,1\}$ points. This result provides a proof the following conjectures of S. Bogatyi, V. Fedorchuk and J. van Mill. Let $f\colon X\to Y$ be a $k$-dimensional map between compact metric spaces with $\dim Y\leq m$. Then: \begin{inparaenum}[\rm(1)] \item there exists a map $h\colon X\to\uin^{m+2k}$ such that $f\triangle h\colon X\to Y\times\uin^{m+2k}$ is 2-to-one provided $k\geq 1$; \item there exists a map $h\colon X\to\uin^{m+k+1}$ such that $f\triangle h\colon X\to Y\times\uin^{m+k+1}$ is $(k+1)$-to-one. \end{inparaenum}
Keywords: finite-to-one maps, dimension, set-valued maps finite-to-one maps, dimension, set-valued maps
MSC Classifications: 54F45, 55M10, 54C65 show english descriptions Dimension theory [See also 55M10]
Dimension theory [See also 54F45]
Selections [See also 28B20]
54F45 - Dimension theory [See also 55M10]
55M10 - Dimension theory [See also 54F45]
54C65 - Selections [See also 28B20]
 

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