Spectra of uniformity
arXiv:1709.04824 · doi:10.14712/1213-7243.2019.008
Abstract
We study some limitations and possible occurrences of uniform ultrafilters on ordinals without the axiom of choice. We prove an Easton-like theorem about the possible spectrum of successors of regular cardinals which carry uniform ultrafilters; we also show that this spectrum is not necessarily closed.
Post-refereeing version; 12 pages