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
Link To Document :
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