English

Nonvanishing Higher Derived Limits without $w\diamondsuit_{\omega_1}$

Logic 2025-08-04 v2

Abstract

We prove a common refinement of theorems of Bergfalk and of Casarosa and Lambie-Hanson, showing that under certain hypotheses, the higher derived limits of a certain inverse system of abelian groups A\mathbf{A} do not vanish. The refined theorem has a number of interesting corollaries, including the nonvanishing of the second derived limit of A\mathbf{A} in many of the common models of set theory of the reals and in the Mitchell model. In particular, we disprove a conjecture of Bergfalk, Hru\v{s}\'ak, and Lambie-Hanson that higher derived limits of A\mathbf{A} vanish in the Miller model.

Keywords

Cite

@article{arxiv.2506.14183,
  title  = {Nonvanishing Higher Derived Limits without $w\diamondsuit_{\omega_1}$},
  author = {Nathaniel Bannister},
  journal= {arXiv preprint arXiv:2506.14183},
  year   = {2025}
}

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16 pages