Topology Proceedings UNIVERSAL LOCALLY COMPACT SCATTERED SPACES

نویسندگان

  • JUAN CARLOS MARTINEZ
  • LAJOS SOUKUP
چکیده

If δ is an ordinal, we denote by C(δ) the class of all cardinal sequences of length δ of locally compact scattered (in short: LCS) spaces. If λ is an infinite cardinal, we write Cλ(δ) = {s ∈ C(δ) : s(0) = λ = min[s(ζ) : ζ < δ]}. An LCS space X is called Cλ(δ)-universal if SEQ(X) ∈ Cλ(δ), and for each sequence s ∈ Cλ(δ) there is an open subspace Y of X with SEQ(Y ) = s. We show that • there is a Cω(ω1)-universal LCS space, • under CH there is a Cω(δ)-universal LCS space for every ordinal δ < ω2, • under GCH for every infinite cardinal λ and every ordinal δ < ω2, there is a Cλ(δ)-universal LCS space, • there may exist a Cω(ω2)-universal LCS space. As a consequence, we obtain that it is consistent that 2 = ω2 and Cω(ω2) is large as possible, i.e. Cω(ω2) = {s ∈ 2{ω, ω1, ω2} : s(0) = ω}. 2000 Mathematics Subject Classification. 54A25, 06E05, 54G12, 03E35.

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تاریخ انتشار 2009