Two inequalities between cardinal invariants

Dilip Raghavan, Saharon Shelah

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

We prove two ZFC inequalities between cardinal invariants. The first inequality involves cardinal invariants associated with an analytic P-ideal, in particular the ideal of subsets of ω of asymptotic density 0. We obtain an upper bound on the ∗-covering number, sometimes also called the weak covering number, of this ideal by proving that cov∗(Z0) k d. Next, we investigate the relationship between the bounding and splitting numbers at regular uncountable cardinals. We prove that, in sharp contrast to the case when k = ω, if k is any regular uncountable cardinal, then sk≤bk.

Original languageEnglish
Pages (from-to)187-200
Number of pages14
JournalFundamenta Mathematicae
Volume237
Issue number2
DOIs
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© Instytut Matematyczny PAN, 2017.

Keywords

  • Asymptotic density
  • Cardinal invariants
  • Dominating number
  • Weakly compact cardinal

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