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A superhigh diamond in the c.e. tt-degrees. (English) Zbl 1216.03054
A computably enumerable set $$A$$ is superhigh if $$A'\equiv_{\text{tt}}0''$$ . In this paper it is proved that there are superhigh computably enumerable sets $$A$$ and $$B$$ such that $${\mathbf 0}$$, $$\text{deg}_{\text{tt}}(A)$$, $$\text{deg}_{\text{tt}}(B)$$, and $${\mathbf 0}'_{\text{tt}}$$ form a diamond in the computably enumerable tt-degrees.

##### MSC:
 03D25 Recursively (computably) enumerable sets and degrees 03D30 Other degrees and reducibilities in computability and recursion theory
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##### References:
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