Turing Degrees in Refinements of the Arithmetical Hierarchy

dc.contributor.author	Selivanov V.
dc.contributor.author	Yamaleev M.
dc.date.accessioned	2019-01-22T20:31:13Z
dc.date.available	2019-01-22T20:31:13Z
dc.date.issued	2018
dc.identifier.issn	0002-5232
dc.identifier.uri	https://dspace.kpfu.ru/xmlui/handle/net/147544
dc.description.abstract	© 2018, Springer Science+Business Media, LLC, part of Springer Nature. We investigate the problem of characterizing proper levels of the fine hierarchy (up to Turing equivalence). It is known that the fine hierarchy exhausts arithmetical sets and contains as a small fragment finite levels of Ershov hierarchies (relativized to ∅n, n < ω), which are known to be proper. Our main result is finding a least new (i.e., distinct from the levels of the relativized Ershov hierarchies) proper level. We also show that not all new levels are proper.
dc.relation.ispartofseries	Algebra and Logic
dc.subject	arithmetical hierarchy
dc.subject	Ershov hierarchy
dc.subject	fine hierarchy
dc.subject	Turing degrees
dc.title	Turing Degrees in Refinements of the Arithmetical Hierarchy
dc.type	Article
dc.relation.ispartofseries-issue	3
dc.relation.ispartofseries-volume	57
dc.collection	Публикации сотрудников КФУ
dc.relation.startpage	222
dc.source.id	SCOPUS00025232-2018-57-3-SID85054185743

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Коллекция содержит публикации сотрудников Казанского федерального (до 2010 года Казанского государственного) университета, проиндексированные в БД Scopus, начиная с 1970г.