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Adjoining cofinitary permutations

Published online by Cambridge University Press:  12 March 2014

Yi Zhang*
Affiliation:
Mathematics Department, Rutgers University, New Brunswick, New Jersey 08903, USA Institute of Mathematics, Academic Sinica, Beijing, 100080, Peoples Republic of China
*
Department of Mathematics and Computer Science, Istanbul Bilgi University, Inonu Caddesi 28, Kustepe Sisli, Istanbul 80310, Turkey, E-mail: cyzhang@math.rutgers.edu

Abstract

We show that it is consistent with ZFC + ¬CH that there is a maximal cofinitary group (or, maximal almost disjoint group) G ≤ Sym(ω) such that G is a proper subset of an almost disjoint family A ⊆ Sym(ω) and ‖G‖ < ‖A‖. We also ask several questions in this area.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1999

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References

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