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Conference Papers Year : 2017

Admissibles in Gaps


We consider clockable ordinals for Infinite Time Turing Machines (ITTMs), i.e., halting times of ITTMs on the empty input. It is well-known that, in contrast to the writable ordinals, the set of clockable ordinals has ‘gaps’. In this paper, we show several results on gaps, mainly related to the admissible ordinals they may properly contain. We prove that any writable ordinal can occur as the order type of the sequence of admissible ordinals in such a gap. We give precise information on their ending points. We also investigate higher rank ordinals (recursively inaccessible, etc.). Moreover, we show that those gaps can have any reasonably effective length (in the sense of ITTMs) compared to their starting point.
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lirmm-02020594 , version 1 (15-02-2019)



Merlin Carl, Bruno Durand, Grégory Lafitte, Sabrina Ouazzani. Admissibles in Gaps. CiE 2017 - 13th Conference on Computability in Europe, Jun 2017, Turku, Finland. pp.175-186, ⟨10.1007/978-3-319-58741-7_18⟩. ⟨lirmm-02020594⟩
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