Displaying similar documents to “On the symmetry of Dini derivates of arbitrary functions”

Inscribing compact non-σ-porous sets into analytic non-σ-porous sets

Miroslav Zelený, Luděk Zajíček (2005)

Fundamenta Mathematicae

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The main aim of this paper is to give a simpler proof of the following assertion. Let A be an analytic non-σ-porous subset of a locally compact metric space, E. Then there exists a compact non-σ-porous subset of A. Moreover, we prove the above assertion also for σ-P-porous sets, where P is a porosity-like relation on E satisfying some additional conditions. Our result covers σ-⟨g⟩-porous sets, σ-porous sets, and σ-symmetrically porous sets.