-discrete decomposability of completely additive families
Borel sets with σ-compact sections for nonseparable spaces
We prove that every (extended) Borel subset E of X × Y, where X is complete metric and Y is Polish, can be covered by countably many extended Borel sets with compact sections if the sections , x ∈ X, are σ-compact. This is a nonseparable version of a theorem of Saint Raymond. As a by-product, we get a proof of Saint Raymond’s result which does not use transfinite induction.
Borel classes of uniformizations of sets with large sections
We give several refinements of known theorems on Borel uniformizations of sets with “large sections”. In particular, we show that a set B ⊂ [0,1] × [0,1] which belongs to , α ≥ 2, and which has all “vertical” sections of positive Lebesgue measure, has a uniformization which is the graph of a -measurable mapping. We get a similar result for sets with nonmeager sections. As a corollary we derive an improvement of Srivastava’s theorem on uniformizations for Borel sets with sections.
Extensions of Borel Measurable Maps and Ranges of Borel Bimeasurable Maps
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.
Remark on completely Baire-additive families in analytic spaces
On a simulation of the oscillation excited by a random force
Generalized analytic spaces, completeness and fragmentability
Classical analytic spaces can be characterized as projections of Polish spaces. We prove analogous results for three classes of generalized analytic spaces that were introduced by Z. Frolík, D. Fremlin and R. Hansell. We use the technique of complete sequences of covers. We explain also some relations of analyticity to certain fragmentability properties of topological spaces endowed with an additional metric.
Čech analytic and almost -descriptive spaces
Foreword
Local and global -cone porosity
Zdeněk Frolík and the descriptive theory of sets and spaces
Binormality of Banach spaces
We study binormality, a separation property of spaces endowed with two topologies known in the real analysis as the Luzin-Menchoff property. The main object of our interest are Banach spaces with their norm and weak topologies. We show that every separable Banach space is binormal and the space is not binormal.
Two remarks on the structure of sets of exposed and extreme points.
-mappings and the invariance of absolute Borel classes
It is proved that -mappings preserve absolute Borel classes, which improves results of R. W. Hansell, J. E. Jayne and C. A. Rogers. The proof is based on the fact that any -mapping f: X → Y of an absolute Suslin metric space X onto an absolute Suslin metric space Y becomes a piecewise perfect mapping when restricted to a suitable -set satisfying .
Selections using orderings (non-separable case)
Descriptive properties of mappings between nonseparable Luzin spaces
We relate some subsets of the product of nonseparable Luzin (e.g., completely metrizable) spaces to subsets of in a way which allows to deduce descriptive properties of from corresponding theorems on . As consequences we prove a nonseparable version of Kondô’s uniformization theorem and results on sets of points in with particular properties of fibres of a mapping . Using these, we get descriptions of bimeasurable mappings between nonseparable Luzin spaces in terms of fibres.
Foreword
Nondifferentiable functions, Haar null sets and Wiener measure
Foreword
Radon spaces which are not -fragmentable
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