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Applications of the Magidor Iteration to Ultrafilter Theory

Logic 2026-04-22 v2

Abstract

We characterize sums of normal ultrafilters after the Magidor iteration (product) of Prikry forcings over a discrete set of measurable cardinals. We apply this to show that the weak Ultrapower Axiom is not equivalent to the Ultrapower Axiom. We also construct a non-rigid ultrapower and two uniform ultrafilters on different cardinals that have the same ultrapower.

Keywords

Cite

@article{arxiv.2412.09683,
  title  = {Applications of the Magidor Iteration to Ultrafilter Theory},
  author = {Tom Benhamou and Gabriel Goldberg},
  journal= {arXiv preprint arXiv:2412.09683},
  year   = {2026}
}