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arXiv · 2212.05318

Definability of maximal cofinitary groups

Severin Mejak·David Schrittesser
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Abstract

We present a proof of a result, previously announced by the second author, that there is a closed (even $\Pi^0_1$) set generating an $F_\sigma$ (even $\Sigma^0_2$) maximal cofinitary group (short, mcg) which is isomorphic to a free group. In this isomorphism class, this is the lowest possible definitional complexity of an mcg.

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Severin Mejak, David Schrittesser. 2022-12-10. Definability of maximal cofinitary groups. https://arxiv.org/abs/2212.05318

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