Abstract
We show that there is a computable procedure which, given an ∀∃-sentence \({\varphi}\) in the language of the partially ordered sets with a top element 1 and a bottom element 0, computes whether \({\varphi}\) is true in the Medvedev degrees of \({\Pi^0_1}\) classes in Cantor space, sometimes denoted by \({\mathcal{P}_s}\) .
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Joshua Cole’s work is part of his PhD thesis at the University of Notre Dame under Peter Cholak. He was supported by a fellowship from the Arthur T. Schmitt Foundation and NSF-DMS-0652669 and NSF-EMSW21-RTG-0739007.
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Cole, J.A., Kihara, T. The ∀∃-theory of the effectively closed Medvedev degrees is decidable. Arch. Math. Logic 49, 1–16 (2010). https://doi.org/10.1007/s00153-009-0150-6
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DOI: https://doi.org/10.1007/s00153-009-0150-6