arXiv 0901.38762009-01math.LO

Lattice initial segments of the Turing degrees

Bjørn Kjos-Hanssen

备注：: Doctoral dissertation, Logic and the Methodology of Science, University of California, Berkeley, 2002

英文摘要：

We characterize the isomorphism types of principal ideals of the Turing degrees below 0' that are lattices as the lattices with a Sigma-0-3 presentation, by showing that each Sigma-0-3 presentable bounded upper semilattice is isomorphic to such a principal ideal. We get a similar result for the Turing degrees below any degree above 0".

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