• 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