In this note a theorem is proved
which includes the following: if T is a consistent, axiomatizable Rosser theory in
which all recursive functions of one argument are definable and S is any sentence
undecidable in T, then given any pair (d1,d2) of re (recursively enumerable)
degrees, there is a formula F which represents a set of degree d1 in T and of
degree d2 in T′ = T(S), the theory obtained from T by adjoining S as a new
axiom.
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