A friendly iteration forcing that the four cardinal characteristics of $\mathcal E$ can be pairwise different
Tom 173 / 2023
Colloquium Mathematicum 173 (2023), 123-157
MSC: Primary 03E17; Secondary 03E05, 03E35, 03E40.
DOI: 10.4064/cm8917-2-2023
Opublikowany online: 11 April 2023
Streszczenie
Let $\mathcal E$ be the $\sigma $-ideal generated by the closed measure zero sets of reals. We use an ultrafilter-extendable matrix iteration of ccc posets to force that, for $\mathcal E$, their associated cardinal characteristics (i.e. additivity, covering, uniformity, and cofinality) are pairwise different.
