Miguel A. Cardona, Diego A. Mejía, Ismael E. Rivera-Madrid
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The covering number of the strong measure zero ideal can be above almost everything else
We show that certain type of tree forcings, including Sacks forcing, increases the covering of the strong measure zero ideal \({{\mathcal {S}}}{{\mathcal {N}}}\). As a consequence, in Sacks model, such covering number is equal to the size of the continuum, which indicates that this covering number is consistently larger than any other classical cardinal invariant of the continuum. Even more, Sacks forcing can be used to force that \(\mathrm {non}({{\mathcal {S}}}{{\mathcal {N}}})<\mathrm {cov}({{\mathcal {S}}}{{\mathcal {N}}})<\mathrm {cof}({{\mathcal {S}}}{{\mathcal {N}}})\), which is the first consistency result where more than two cardinal invariants associated with \({{\mathcal {S}}}{{\mathcal {N}}}\) are pairwise different. Another consequence is that \({{\mathcal {S}}}{{\mathcal {N}}}\subseteq s^0\) in ZFC where \(s^0\) denotes Marczewski’s ideal.
期刊介绍:
The journal publishes research papers and occasionally surveys or expositions on mathematical logic. Contributions are also welcomed from other related areas, such as theoretical computer science or philosophy, as long as the methods of mathematical logic play a significant role. The journal therefore addresses logicians and mathematicians, computer scientists, and philosophers who are interested in the applications of mathematical logic in their own field, as well as its interactions with other areas of research.