Switch to: References

Add citations

You must login to add citations.
  1. Inside the Muchnik degrees II: The degree structures induced by the arithmetical hierarchy of countably continuous functions.K. Higuchi & T. Kihara - 2014 - Annals of Pure and Applied Logic 165 (6):1201-1241.
    It is known that infinitely many Medvedev degrees exist inside the Muchnik degree of any nontrivial Π10 subset of Cantor space. We shed light on the fine structures inside these Muchnik degrees related to learnability and piecewise computability. As for nonempty Π10 subsets of Cantor space, we show the existence of a finite-Δ20-piecewise degree containing infinitely many finite-2-piecewise degrees, and a finite-2-piecewise degree containing infinitely many finite-Δ20-piecewise degrees 2 denotes the difference of two Πn0 sets), whereas the greatest degrees in (...)
    Download  
     
    Export citation  
     
    Bookmark   1 citation  
  • Coding true arithmetic in the Medvedev degrees of classes.Paul Shafer - 2012 - Annals of Pure and Applied Logic 163 (3):321-337.
    Download  
     
    Export citation  
     
    Bookmark   1 citation  
  • Characterizing the Join-Irreducible Medvedev Degrees.Paul Shafer - 2011 - Notre Dame Journal of Formal Logic 52 (1):21-38.
    We characterize the join-irreducible Medvedev degrees as the degrees of complements of Turing ideals, thereby solving a problem posed by Sorbi. We use this characterization to prove that there are Medvedev degrees above the second-least degree that do not bound any join-irreducible degrees above this second-least degree. This solves a problem posed by Sorbi and Terwijn. Finally, we prove that the filter generated by the degrees of closed sets is not prime. This solves a problem posed by Bianchini and Sorbi.
    Download  
     
    Export citation  
     
    Bookmark   5 citations  
  • A hierarchy of immunity and density for sets of reals.Takayuki Kihara - 2012 - In S. Barry Cooper (ed.), How the World Computes. pp. 384--394.
    Download  
     
    Export citation  
     
    Bookmark  
  • Comparing the degrees of enumerability and the closed Medvedev degrees.Paul Shafer & Andrea Sorbi - 2019 - Archive for Mathematical Logic 58 (5-6):527-542.
    We compare the degrees of enumerability and the closed Medvedev degrees and find that many situations occur. There are nonzero closed degrees that do not bound nonzero degrees of enumerability, there are nonzero degrees of enumerability that do not bound nonzero closed degrees, and there are degrees that are nontrivially both degrees of enumerability and closed degrees. We also show that the compact degrees of enumerability exactly correspond to the cototal enumeration degrees.
    Download  
     
    Export citation  
     
    Bookmark