  Xiang Li (1983) introduced what are now called constructively immune sets as
an effective version of immunity. Such have been studied in relation to
randomness and minimal indices, and we add another application area: numberings
of the rationals. We also investigate the Turing degrees of constructively
immune sets and the closely related $\Sigma^0_1$-dense sets of Ferbus-Zanda and
Grigorieff (2008).

Logic