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arXiv · 2209.06898

Borel complexity of modules

Michael C. Laskowski·Danielle S. Ulrich
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Abstract

We prove that for a countable, commutative ring $R$, the class of countable $R$-modules either has only countably many isomorphism types, or else it is Borel complete. The machinery gives a succinct proof of the Borel completeness of TFAB, the class of torsion-free abelian groups. We also prove that for any countable ring $R$, both the class of left $R$-modules endowed with an endomorphism and the class of left $R$-modules with four named submodules are Borel complete.

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Michael C. Laskowski, Danielle S. Ulrich. 2022-09-14. Borel complexity of modules. https://arxiv.org/abs/2209.06898

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