Separating cardinal characteristics of the strong measure zero ideal

Jörg Brendle, Miguel A. Cardona, Diego A. Mejía

Published 2023-09-05Version 1

Let $\mathcal{SN}$ be the $\sigma$-ideal of the strong measure zero sets of reals. We present general properties of forcing notions that allow to control of the additivity of $\mathcal{SN}$ after finite support iterations. This is applied to force that the four cardinal characteristics associated with $\mathcal{SN}$ are pairwise different: \[\mathrm{add}(\mathcal{SN})<\mathrm{cov}(\mathcal{SN})<\mathrm{non}(\mathcal{SN})<\mathrm{cof}(\mathcal{SN}).\] 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).