INTROENUMERABILITY, AUTOREDUCIBILITY, AND RANDOMNESS.

We define upper Psi $\Psi $ Ψ -autoreducible sets given an autoreduction procedure upper Psi $\Psi $ Ψ. Then, we show that for any upper Psi $\Psi $ Ψ , a measurable class of upper Psi $\Psi $ Ψ -autoreducible sets has measure zero. Using this, we show that classes of cototal, uniformly introenumera...

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Detalles Bibliográficos
Publicado en:Journal of Symbolic Logic Vol. 91; no. 2; pp. 617 - 626
Autor principal: LI, ANG
Formato: Artículo
Publicado: Cambridge University Press Jun2026
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Acceso en línea:Ver este registro en EBSCOhost
Descripción
Sumario:We define upper Psi $\Psi $ Ψ -autoreducible sets given an autoreduction procedure upper Psi $\Psi $ Ψ. Then, we show that for any upper Psi $\Psi $ Ψ , a measurable class of upper Psi $\Psi $ Ψ -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 upper Psi $\Psi $ Ψ -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.