Title of article
Compact covering and game determinacy
Author/Authors
Debs، نويسنده , , Gabriel and Raymond، نويسنده , , Jean Saint، نويسنده ,
Issue Information
دوماهنامه با شماره پیاپی سال 1996
Pages
33
From page
153
To page
185
Abstract
All spaces are separable and metrizable. Suppose that the continuous and onto mapping t́f : X → Y is compact covering. Under the axiom of ∑11-determinacy, we prove that t́f is inductively perfect whenever X is Borel, and it follows then that Y is also Borel. Under the axiom ℵ1L = ℵ1 we construct examples showing that the conclusion might fail if “X is Borel” is replaced by “X is coanalytic”. If we suppose that both X and Y are Borel, then we prove (in ZFC) the weaker conclusion that t́f has a Borel (in fact a Baire-1) section g : Y → X. We also prove (in ZFC) that if we suppose only X to be Borel but of some “low” class, then Y is also Borel of the same class. Other related problems are discussed.
Keywords
Determinacy , Compact covering , Inductively perfect
Journal title
Topology and its Applications
Serial Year
1996
Journal title
Topology and its Applications
Record number
1578802
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