English

Effective bi-immunity and randomness

Logic 2017-09-27 v2

Abstract

We study the relationship between randomness and effective bi-immunity. Greenberg and Miller have shown that for any oracle X, there are arbitrarily slow-growing DNR functions relative to X that compute no ML random set. We show that the same holds when ML randomness is replaced with effective bi-immunity. It follows that there are sequences of effective Hausdorff dimension 1 that compute no effectively bi-immune set. We also establish an important difference between the two properties. The class Low(MLR, EBI) of oracles relative to which every ML random is effectively bi-immune contains the jump-traceable sets, and is therefore of cardinality continuum.

Cite

@article{arxiv.1610.08615,
  title  = {Effective bi-immunity and randomness},
  author = {Achilles A. Beros and Mushfeq Khan and Bjørn Kjos-Hanssen},
  journal= {arXiv preprint arXiv:1610.08615},
  year   = {2017}
}

Comments

10

R2 v1 2026-06-22T16:33:25.210Z