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JOURNALS // Sibirskii Matematicheskii Zhurnal // Archive

Sibirsk. Mat. Zh., 2017 Volume 58, Number 6, Pages 1418–1427 (Mi smj2948)

This article is cited in 9 papers

The Rogers semilattices of generalized computable enumerations

M. Kh. Faizrahmanov

Kazan (Volga Region) Federal University, Lobachevskiĭ Institute of Mathematics and Mechanics, Kazan, Russia

Abstract: We study the cardinality and structural properties of the Rogers semilattice of generalized computable enumerations with arbitrary noncomputable oracles and oracles of hyperimmune Turing degree. We show the infinity of the Rogers semilattice of generalized computable enumerations of an arbitrary nontrivial family with a noncomputable oracle. In the case of oracles of hyperimmune degree we prove that the Rogers semilattice of an arbitrary infinite family includes an ideal without minimal elements and establish that the top, if present, is a limit element under the condition that the family contains the inclusion-least set.

Keywords: computable enumeration, generalized computable enumeration, Rogers semilattice, hyperimmune set, minimal enumeration, universal enumeration.

UDC: 510.57

MSC: 35R30

Received: 16.11.2016

DOI: 10.17377/smzh.2017.58.619


 English version:
Siberian Mathematical Journal, 2017, 58:6, 1104–1110

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© Steklov Math. Inst. of RAS, 2025