Autostability spectra for decidable structures

We study autostability spectra relative to strong constructivizations (SC-autostability spectra). For a decidable structure $\mathcal{S}$ , the SC-autostability spectrum of $\mathcal{S}$ is the set of all Turing degrees capable of computing isomorphisms among arbitrary decidable copies of $\mathcal{...

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Veröffentlicht in:Mathematical structures in computer science 2018-03, Vol.28 (3), p.392-411
1. Verfasser: BAZHENOV, NIKOLAY
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Sprache:eng
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Zusammenfassung:We study autostability spectra relative to strong constructivizations (SC-autostability spectra). For a decidable structure $\mathcal{S}$ , the SC-autostability spectrum of $\mathcal{S}$ is the set of all Turing degrees capable of computing isomorphisms among arbitrary decidable copies of $\mathcal{S}$ . The degree of SC-autostability for $\mathcal{S}$ is the least degree in the spectrum (if such a degree exists). We prove that for a computable successor ordinal α, every Turing degree c.e. in and above 0 (α) is the degree of SC-autostability for some decidable structure. We show that for an infinite computable ordinal β, every Turing degree c.e. in and above 0 (2β+1) is the degree of SC-autostability for some discrete linear order. We prove that the set of all PA-degrees is an SC-autostability spectrum. We also obtain similar results for autostability spectra relative to n-constructivizations.
ISSN:0960-1295
1469-8072
DOI:10.1017/S096012951600030X