English

Introenumerability, autoreducibility, and randomness

Logic 2024-02-14 v1

Abstract

We define Ψ\Psi-autoreducible sets given an autoreduction procedure Ψ\Psi. Then, we show that for any Ψ\Psi, a measurable class of Ψ\Psi-autoreducible sets has measure zero. Using this, we show that classes of cototal, uniformly introenumerable, introenumerable, and hyper-cototal enumeration degrees all have measure zero. By analyzing the arithmetical complexity of the classes of cototal sets and cototal enumeration degrees, we show that weakly 2-random sets cannot be cototal and weakly 3-random sets cannot be of cototal enumeration degree. Then, we see that this result is optimal by showing that there exists a 1-random cototal set and a 2-random set of cototal enumeration degree. For uniformly introenumerable degrees and introenumerable degrees, we utilize Ψ\Psi-autoreducibility again to show the optimal result that no weakly 3-random sets can have introenumerable enumeration degree. We also show that no 1-random set can be introenumerable.

Keywords

Cite

@article{arxiv.2402.08247,
  title  = {Introenumerability, autoreducibility, and randomness},
  author = {Ang Li},
  journal= {arXiv preprint arXiv:2402.08247},
  year   = {2024}
}
R2 v1 2026-06-28T14:47:00.439Z