Continuous images of closed sets in generalized Baire spaces

Philipp Lücke, Philipp Schlicht

Research output: Contribution to journalArticle (Academic Journal)peer-review

11 Citations (Scopus)
119 Downloads (Pure)

Abstract

Let κ be an uncountable cardinal with κ=κ<κ. Given a cardinal µ, we equip the set κμ consisting of all functions from κ to μ with the topology whose basic open sets consist of all extensions of partial functions of cardinality less than κ. We prove results that allow us to separate several classes of subsets of κκ that consist of continuous images of closed subsets of spaces of the form κμ. Important examples of such results are the following: (i) there is a closed subset of κκ that is not a continuous image of κκ; (ii) there is an injective continuous image of κκ that is not κ-Borel (i.e., that is not contained in the smallest algebra of sets on κκ that contains all open subsets and is closed under κ-unions); (iii) the statement “every continuous image of κκ is an injective continuous image of a closed subset of κκ” is independent of the axioms of ZFC; and (iv) the axioms of ZFC do not prove that the assumption “2κ>κ+” implies the statement “every closed subset of κκ is a continuous image of κ(κ+)” or its negation.
Original languageEnglish
Pages (from-to)421-461
Number of pages41
JournalIsrael Journal of Mathematics
Volume209
DOIs
Publication statusPublished - 31 Oct 2015

Keywords

  • closed subset
  • continuous image
  • dense open subset
  • regular cardinal
  • direct successor

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