The ultrafilter and almost disjointness numbers
| Autor: | Guzman, Osvaldo, Kalajdzievski, Damjan |
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| Rok vydání: | 2020 |
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| Druh dokumentu: | Working Paper |
| Popis: | We prove that every MAD family can be destroyed by a proper forcing that preserves $P$-points. With this result, we prove that it is consistent that $\omega_{1}=\mathfrak{u}<\mathfrak{a,}$ solving a nearly 20 year old problem of Shelah and a problem of Brendle. We will also present a simple proof of a result of Blass and Shelah that the inequality $\mathfrak{u |
| Databáze: | arXiv |
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