Journal of Symbolic Logic · 1998 · 23 citations · 7 references
Natural SciencesComputer ScienceMathematicsCombinatoricsNumber TheorySet TheoryCombinatorial EnumerationCombinatorial Set TheoryEnumerative CombinatoricsPartial OrdersEnumerabilityFinite Difference Methods In EnumerationHierarchy
Abstract We show that the intersection of the class of 2-REA degrees with that of the ω-r.e. degrees consists precisely of the class of d.r.e. degrees. We also include some applications and show that there is no natural generalization of this result to higher levels of the REA hierarchy.
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Recursively enumerable sets and degrees
Robert I. Soare · Bulletin of the American Mathematical Society · 1978 · 1.6K citations · Full text
Yu. L. Ershov · Algebra and Logic · 1968 · 131 citations