Template iterations and maximal cofinitary groups
| Autor: | Vera Fischer, Asger Törnquist |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Fundamenta Mathematicae. 230:205-236 |
| ISSN: | 1730-6329 0016-2736 |
| DOI: | 10.4064/fm230-3-1 |
| Popis: | The main result of the present paper is that $\mathfrak a_g$, the minimal size of maximal cofinitary group, can be of countable cofinality. To prove this we define a natural poset for adding a maximal cofinitary group of a given cardinality, which enjoys certain combinatorial properties allowing it to be used within a similar template forcing construction. Additionally we obtain that $\mathfrak a_p$, the minimal size of a maximal family of almost disjoint permutations, and $\mathfrak a_e$, the minimal size of a maximal eventually different family, can be of countable cofinality. 24 pages |
| Databáze: | OpenAIRE |
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