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This article is cited in 4 scientific papers (total in 4 papers)
The universal Lachlan semilattice without the greatest element
S. Yu. Podzorov
Abstract:
We deal with some upper semilattices of $m$-degrees and of numberings of finite families. It is proved that the semilattice of all c.e. $m$-degrees, from which the greatest element is removed, is isomorphic to the semilattice of simple $m$-degrees, the semilattice of hypersimple $m$-degrees, and the semilattice of $\Sigma_2^0$-computable numberings of a finite family of $\Sigma_2^0$-sets, which contains more than one element and does not contain elements that are comparable w.r.t. inclusion.
Keywords:
upper semilattice, distributive semilattice, $m$-degree, numbering, Rogers semilattice, Lachlan semilattice.
Received: 24.06.2006 Revised: 21.02.2007
Citation:
S. Yu. Podzorov, “The universal Lachlan semilattice without the greatest element”, Algebra Logika, 46:3 (2007), 299–345; Algebra and Logic, 46:3 (2007), 163–187
Linking options:
https://www.mathnet.ru/eng/al299 https://www.mathnet.ru/eng/al/v46/i3/p299
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Abstract page: | 370 | Full-text PDF : | 131 | References: | 44 | First page: | 4 |
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