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On the complexity of the theory of a computably presented metric structure
Archive For Mathematical Logic ( IF 0.3 ) Pub Date : 2023-06-09 , DOI: 10.1007/s00153-023-00884-4
Caleb Camrud , Isaac Goldbring , Timothy H. McNicholl

We consider the complexity (in terms of the arithmetical hierarchy) of the various quantifier levels of the diagram of a computably presented metric structure. As the truth value of a sentence of continuous logic may be any real in [0, 1], we introduce two kinds of diagrams at each level: the closed diagram, which encapsulates weak inequalities of the form \(\phi ^\mathcal {M}\le r\), and the open diagram, which encapsulates strict inequalities of the form \(\phi ^\mathcal {M}< r\). We show that the closed and open \(\Sigma _N\) diagrams are \(\Pi ^0_{N+1}\) and \(\Sigma ^0_N\) respectively, and that the closed and open \(\Pi _N\) diagrams are \(\Pi ^0_N\) and \(\Sigma ^0_{N + 1}\) respectively. We then introduce effective infinitary formulas of continuous logic and extend our results to the hyperarithmetical hierarchy. Finally, we demonstrate that our results are optimal.



中文翻译:

关于可计算呈现的度量结构理论的复杂性

我们考虑了可计算呈现的度量结构图的各种量词级别的复杂性(就算术层次而言)。由于连续逻辑语句的真值可能是 [0, 1] 中的任何实数,我们在每个级别引入两种图:闭合图,它封装了 \(\phi ^ \ mathcal { M}\le r\)打开的图,它封装了形式为\(\phi ^\mathcal {M}< r\)的严格不等式。我们证明了闭图和开图\(\Sigma _N\)分别是\(\Pi ^0_{N+1}\)\(\Sigma ^0_N\),闭图和开图\(\Pi _N\)图分别是\(\Pi ^0_N\)\(\Sigma ^0_{N + 1}\) 。然后,我们引入连续逻辑的有效无限公式,并将我们的结果扩展到超算术层次结构。最后,我们证明我们的结果是最优的。

更新日期:2023-06-10
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