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}
}
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