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JC
2000
89views more  JC 2000»
13 years 10 months ago
Weakly Computable Real Numbers
The Turing degree of a real number x is defined as the Turing degree of its binary expansion. This definition is quite natural and robust. In this paper we discuss some basic degr...
Klaus Ambos-Spies, Klaus Weihrauch, Xizhong Zheng
APAL
2005
88views more  APAL 2005»
13 years 10 months ago
Completing pseudojump operators
We investigate operators which take a set X to a set relatively computably enumerable in and above X by studying which such sets X can be so mapped into the Turing degree of K. We...
Richard Coles, Rodney G. Downey, Carl G. Jockusch ...
MSCS
2006
69views more  MSCS 2006»
13 years 10 months ago
Restricted jump interpolation in the d.c.e. degrees
It is shown that for any 2-computably enumerable Turing degree l, any computably enumerable degree a, and any Turing degree s, if l = 0 , l < a, s 0 , and s is c.e. in a, then...
Carl G. Jockusch Jr., Angsheng Li
APAL
2010
68views more  APAL 2010»
13 years 11 months ago
Spaces of orders and their Turing degree spectra
We investigate computability theoretic and topological properties of spaces of orders on computable orderable groups. A left order on a group G is a linear order of the domain of ...
Malgorzata A. Dabkowska, Mieczyslaw K. Dabkowski, ...
BIRTHDAY
2010
Springer
14 years 2 hour ago
Halting and Equivalence of Program Schemes in Models of Arbitrary Theories
In this note we consider the following decision problems. Let be a fixed first-order signature. (i) Given a first-order theory or ground theory T over of Turing degree , a program...
Dexter Kozen
CIE
2005
Springer
14 years 4 months ago
On a Question of Sacks - A Partial Solution on the Positive Side
Let us say that a c.e. operator E is degree invariant on any given Turing degree a if X, Y ∈ a → E(X) ≡T E(Y ). In [4] we construct a c.e. operator E such that ∀X[X <T E...
Andrew E. M. Lewis
CIE
2009
Springer
14 years 5 months ago
Index Sets and Universal Numberings
This paper studies the Turing degrees of various properties defined for universal numberings, that is, for numberings which list all partial-recursive functions. In particular pro...
Sanjay Jain, Frank Stephan, Jason Teutsch