English

Usuba's principle $UB_\lambda$ can fail at singular cardinals

Logic 2023-10-27 v4

Abstract

We answer a question of Usuba by showing that the combinatorial principle UBλUB_\lambda can fail at a singular cardinal. Furthermore, λ\lambda can be taken to be ω.\aleph_\omega.

Cite

@article{arxiv.2107.09339,
  title  = {Usuba's principle $UB_\lambda$ can fail at singular cardinals},
  author = {Mohammad Golshani and Saharon Shelah},
  journal= {arXiv preprint arXiv:2107.09339},
  year   = {2023}
}

Comments

Paper number 1216 second author. Accepted for Journal of Symbolic Logic

R2 v1 2026-06-24T04:21:12.999Z