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Permutation Groups and Ideals of Turing Degrees

  • A. S. Morozov,
  • V. G. Puzarenko,
  • M. Kh. Faizrakhmanov

摘要

We study degrees and degree spectra of groups \({\mathfrak{G}}_{\mathrm{I}}\) G I defined on a set of permutations of the natural numbers ω whose degrees belong to a Turing ideal I. A necessary condition and a sufficient condition are stated which specify whether an arbitrary Turing degree belongs to the degree spectrum of a group \({\mathfrak{G}}_{\mathrm{I}}\) G I . Nonprincipal ideals I for which the group \({\mathfrak{G}}_{\mathrm{I}}\) G I has or does not have a degree are exemplified.