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  1. Relative Enumerability in the Difference Hierarchy.Marat M. Arslanov, Geoffrey L. Laforte & Theodore A. Slaman - 1998 - Journal of Symbolic Logic 63 (2):411-420.
    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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  • 2001 Annual Meeting of the Association for Symbolic Logic.Andre Scedrov - 2001 - Bulletin of Symbolic Logic 7 (3):420-435.
  • Isolation and Lattice Embeddings.Guohua Wu - 2002 - Journal of Symbolic Logic 67 (3):1055-1064.
    Say that (a, d) is an isolation pair if a is a c.e. degree, d is a d.c.e. degree, a < d and a bounds all c.e. degrees below d. We prove that there are an isolation pair (a, d) and a c.e. degree c such that c is incomparable with a, d, and c cups d to o', caps a to o. Thus, {o, c, d, o'} is a diamond embedding, which was first proved by Downey in [9]. Furthermore, (...)
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  • 1998–99 Annual Meeting of the Association for Symbolic Logic.Sam Buss - 1999 - Bulletin of Symbolic Logic 5 (3):395-421.
  • Nonisolated Degrees and the Jump Operator.Guohua Wu - 2002 - Annals of Pure and Applied Logic 117 (1-3):209-221.
    Say that a d.c.e. degree d is nonisolated if for any c.e. degree a
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  • Complementing Cappable Degrees in the Difference Hierarchy.Rod Downey, Angsheng Li & Guohua Wu - 2004 - Annals of Pure and Applied Logic 125 (1-3):101-118.
    We prove that for any computably enumerable degree c, if it is cappable in the computably enumerable degrees, then there is a d.c.e. degree d such that c d = 0′ and c ∩ d = 0. Consequently, a computably enumerable degree is cappable if and only if it can be complemented by a nonzero d.c.e. degree. This gives a new characterization of the cappable degrees.
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  • An Interval of Computably Enumerable Isolating Degrees.Matthew C. Salts - 1999 - Mathematical Logic Quarterly 45 (1):59-72.
    We construct computably enumerable degrees a < b such that all computably enumerable degrees c with a < c < b isolate some d. c. e. degree d.
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  • Bi-Isolation in the D.C.E. Degrees.Guohua Wu - 2004 - Journal of Symbolic Logic 69 (2):409 - 420.
    In this paper, we study the bi-isolation phenomena in the d.c.e. degrees and prove that there are c.e. degrees c₁ < c₂ and a d.c.e. degree d ∈ (c₁, c₂) such that (c₁, d) and (d, c₂) contain no c.e. degrees. Thus, the c.e. degrees between c₁ and c₂ are all incomparable with d. We also show that there are d.c.e. degrees d₁ < d₂ such that (d₁, d₂) contains a unique c.e. degree.
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  • Bi-Isolation in the D.C.E. Degrees.Guohua Wu - 2004 - Journal of Symbolic Logic 69 (2):409-420.
    In this paper, we study the bi-isolation phenomena in the d.c.e. degrees and prove that there are c.e. degrees c1 < c2 and a d.c.e. degree d∈ such that and contain no c.e. degrees. Thus, the c.e. degrees between c1 and c2 are all incomparable with d. We also show that there are d.c.e. degrees d1 < d2 such that contains a unique c.e. degree.
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