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A+ CATEGORY SCIENTIFIC UNIT

The splitting number can be smaller than the matrix chaos number

Volume 171 / 2002

Heike Mildenberger, Saharon Shelah Fundamenta Mathematicae 171 (2002), 167-176 MSC: 03E15, 03E17, 03E35. DOI: 10.4064/fm171-2-4

Abstract

Let be the minimum cardinality of a subset of {}^\omega 2 that cannot be made convergent by multiplication with a single Toeplitz matrix. By an application of a creature forcing we show that {\frak s} < \chi is consistent. We thus answer a question by Vojtáš. We give two kinds of models for the strict inequality. The first is the combination of an \aleph _2-iteration of some proper forcing with adding \aleph _1 random reals. The second kind of models is obtained by adding \delta random reals to a model of {\rm MA}_{<\kappa } for some \delta \in [\aleph _1,\kappa ). It was a conjecture of Blass that {\frak s}=\aleph _1 < \chi = \kappa holds in such a model. For the analysis of the second model we again use the creature forcing from the first model.

Authors

  • Heike MildenbergerInstitut für formale Logik
    Universität Wien
    Währinger Str. 25
    A-1090 Vienna, Austria
    e-mail
  • Saharon ShelahInstitute of Mathematics
    The Hebrew University of Jerusalem
    Givat Ram
    91904 Jerusalem, Israel
    e-mail

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