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# Wydawnictwa / Czasopisma IMPAN / Bulletin Polish Acad. Sci. Math. / Wszystkie zeszyty

## Extensions of Borel Measurable Maps and Ranges of Borel Bimeasurable Maps

### Tom 52 / 2004

Bulletin Polish Acad. Sci. Math. 52 (2004), 151-167 MSC: 26A21, 28A05, 54H05. DOI: 10.4064/ba52-2-6

#### Streszczenie

We prove an abstract version of the Kuratowski extension theorem for Borel measurable maps of a given class. It enables us to deduce and improve its nonseparable version due to Hansell. We also study the ranges of not necessarily injective Borel bimeasurable maps $f$ and show that some control on the relative classes of preimages and images of Borel sets under $f$ enables one to get a bound on the absolute class of the range of $f$. This seems to be of some interest even within separable spaces.

#### Autorzy

• Petr HolickýDepartment of Mathematical Analysis
Charles University
Sokolovská 83
186 00 Praha 8, Czech Republic
e-mail

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