• Title of article

    Closed maps on spaces with point-countable bases

  • Author/Authors

    Tsugunori and Shibakov، نويسنده , , Alexander، نويسنده ,

  • Issue Information
    دوماهنامه با شماره پیاپی سال 1999
  • Pages
    14
  • From page
    1
  • To page
    14
  • Abstract
    We prove a version of Lašnevʹs theorem for spaces with point-countable bases. m. Let X have a point-countable base, f:X→Y be a closed map. Then there is an ω1-relatively-discrete subspace Z of Y such that |Z|≤d(Y) and f−1(y) is compact for every y∈Y\Z. e study the subspaces of closed images of regular spaces with point-countable bases and show that every such subspace has countable π-character and a point-countable π-base. The latter result is extended to a wider class of spaces which is invariant under closed maps and products with metrizable compacta. The proofs use a structure which controls the convergence properties of the space and those of its closed image.
  • Keywords
    ?-character , Point-countable base , Sequential order , ?-base , Closed map , Sequential space , La?nevיs theorem
  • Journal title
    Topology and its Applications
  • Serial Year
    1999
  • Journal title
    Topology and its Applications
  • Record number

    1579440