Relative to any non-arithmetic set

Fuente: arXiv
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Autor principal: Harrison-Trainor, Matthew
Formato: Preprint
Publicado: 2025
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author Harrison-Trainor, Matthew
author_facet Harrison-Trainor, Matthew
contents Given a countable structure $\mathcal{A}$, the degree spectrum of $\mathcal{A}$ is the set of all Turing degrees which can compute an isomorphic copy of $\mathcal{A}$. One of the major programs in computable structure theory is to determine which (upwards closed, Borel) classes of degrees form a degree spectrum. We resolve one of the major open problems in this area by showing that the non-arithmetic degrees are a degree spectrum. Our main new tool is a new form of unfriendly jump inversions where the back-and-forth types are maximally complicated. This new tool has several other applications.
format Preprint
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publishDate 2025
record_format arxiv
spellingShingle Relative to any non-arithmetic set
Harrison-Trainor, Matthew
Logic
Given a countable structure $\mathcal{A}$, the degree spectrum of $\mathcal{A}$ is the set of all Turing degrees which can compute an isomorphic copy of $\mathcal{A}$. One of the major programs in computable structure theory is to determine which (upwards closed, Borel) classes of degrees form a degree spectrum. We resolve one of the major open problems in this area by showing that the non-arithmetic degrees are a degree spectrum. Our main new tool is a new form of unfriendly jump inversions where the back-and-forth types are maximally complicated. This new tool has several other applications.
title Relative to any non-arithmetic set
topic Logic
url https://arxiv.org/abs/2505.23613