Non‐isolated quasi‐degrees

Mathematical Logic Quarterly 55 (6):587-597 (2009)
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Abstract

We show that non-isolated from below 2-c.e. Q -degrees are dense in the structure of c.e. Q -degrees. We construct a 2-c.e. Q -degree, which can't be isolated from below not only by c.e. Q -degrees, but by any Q -degree. We also prove that below any c.e. Q -degree there is a 2-c.e. Q -degree, which is non-isolated from below and from above

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10.1002/malq.200810026

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Citations of this work

Some structural properties of quasi-degrees.Roland Sh Omanadze - 2018 - Logic Journal of the IGPL 26 (1):191-201.

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Computably enumerable sets and quasi-reducibility.R. Downey, G. LaForte & A. Nies - 1998 - Annals of Pure and Applied Logic 95 (1-3):1-35.

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