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Cupping and definability in the local structure of the enumeration degrees
Published online by Cambridge University Press: 12 March 2014
Abstract
We show that every splitting of in the local structure of the enumeration degrees,
, contains at least one low-cuppable member. We apply this new structural property to show that the classes of all
-pairs in
, all downwards properly
enumeration degrees and all upwards properly
enumeration degrees are first order definable in
.
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- Research Article
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- Copyright © Association for Symbolic Logic 2012
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