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Properly Σ 2 minimal degrees and 0″ complementation
Author(s) -
Barry Cooper S.,
Lewis Andrew E. M.,
Yang Yue
Publication year - 2005
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/malq.200410027
Subject(s) - complement (music) , turing , degree (music) , mathematics , complementation , join (topology) , combinatorics , discrete mathematics , computer science , programming language , biology , genetics , physics , gene , acoustics , phenotype
We show that there exists a properly Σ 2 minimal (Turing) degree b , and moreover that b can be chosen to join with 0 ′ to 0 ″ – so that b is a 0 ″ complement for every degree a such that 0 ′ ≤ a < 0 ″. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)