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Separating cardinal characteristics of the strong measure zero ideal

Logic 2025-08-21 v2

Abstract

Let SN\mathcal{SN} be the σ\sigma-ideal of the strong measure zero sets of reals. We present general properties of forcing notions that allow to control of the additivity of SN\mathcal{SN} after finite support iterations. This is applied to force that the four cardinal characteristics associated with SN\mathcal{SN} are pairwise different: add(SN)<cov(SN)<non(SN)<cof(SN).\mathrm{add}(\mathcal{SN})<\mathrm{cov}(\mathcal{SN})<\mathrm{non}(\mathcal{SN})<\mathrm{cof}(\mathcal{SN}). Furthermore, we construct a forcing extension satisfying the above and Cicho\'n's maximum (i.e.\ that the non-dependent values in Cicho\'n's diagram are pairwise different).

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Cite

@article{arxiv.2309.01931,
  title  = {Separating cardinal characteristics of the strong measure zero ideal},
  author = {Jörg Brendle and Miguel A. Cardona and Diego A. Mejía},
  journal= {arXiv preprint arXiv:2309.01931},
  year   = {2025}
}

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