English

On the possible values of the Rearrangement Number

Logic 2026-07-21 v1 Combinatorics

Abstract

The rearrangement number rr\mathfrak{rr} is the least cardinality of a collection of permutations of ω\omega such that every conditionally convergent real series is disrupted by some permutation in the collection. Blass, Brendle, Brian, Hamkins, Hardy, and Larson proved that max{cov(N),b}rrnon(M)\max\{\operatorname{cov}(\mathcal N),\mathfrak b\}\leq\mathfrak{rr}\leq\operatorname{non}(\mathcal M) and asked whether rr<non(M)\mathfrak{rr}<\mathrm{non}(\mathcal M) is consistent. We prove that rr<non(M)\mathfrak{rr}<\operatorname{non}(\mathcal M) is consistent with ZFC. We also prove, in a different forcing extension, that max{cov(N),b}<rr\max\{\operatorname{cov}(\mathcal N),\mathfrak b\}<\mathfrak{rr}. We further derive consequences for the subseries number ssub\mathfrak{s}_{\mathrm{sub}} and the splitting number s\mathfrak s.

Keywords

Cite

@article{arxiv.2607.18726,
  title  = {On the possible values of the Rearrangement Number},
  author = {Vinicius de Oliveira Rodrigues},
  journal= {arXiv preprint arXiv:2607.18726},
  year   = {2026}
}