The spectrum of characters of ultrafilters on omega

2006/12/09 by Saharon Shelah, Shelah, Saharon
Mathematics · #FOS: Mathematics #General Topology (math.GN) #Logic (math.LO) #math.GN #math.LO

paper · pdf · doi:10.48550/arxiv.math/0612240

published as Colloq. Math. 111 No. 2 (2008) 213--220

arxiv created 2007/08/15 · arxiv updated 2009/12/01

Abstract

We show the consistency of the set of regular cardinals which are the character of some ultrafilter on omega is not convex. We also deal with the set of pi chi-characters of ultrafilters on omega.

Related

• The character spectrum of beta(N)
• Ultrafilters on omega --- their ideals and their cardinal\n characteristics
• The combinatorics of reasonable ultrafilters
• Ultrafilters on omega
• A small ultrafilter number at smaller cardinals