A single minimal complement for the c. e. degrees

We show that there exists a minimal (Turing) degree b < 0' such that for all non-zero c. e. degrees a, 0' = a. b. Since b is minimal this means that b complements all c. e. degrees other than 0 and 0'. Since every n-c.e. degree bounds a non-zero c. e. degree, b complements every n-c.e. degree other than 0 and 0'.