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 |
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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. |
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ISSN: | 0960-1295 1469-8072 |
DOI: | 10.1017/S096012951600030X |