CHARACTERIZING LOWNESS FOR DEMUTH RANDOMNESS.

We show the existence of noncomputable oracles which are low for Demuth randomness, answering a question in [15] (also Problem 5.5.19 in [34]). We fully characterize lowness for Demuth randomness using an appropriate notion of traceability. Central to this characterization is a partial relativizatio...

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Detalles Bibliográficos
Publicado en:Journal of Symbolic Logic Vol. 79; no. 2; pp. 526 - 561
Autores principales: BIENVENU, LAURENT, DOWNEY, ROD, GREENBERG, NOAM, NIES, ANDRÉ, TURETSKY, DAN
Formato: Artículo
Publicado: Cambridge University Press Jun2014
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Acceso en línea:Ver este registro en EBSCOhost
Descripción
Sumario:We show the existence of noncomputable oracles which are low for Demuth randomness, answering a question in [15] (also Problem 5.5.19 in [34]). We fully characterize lowness for Demuth randomness using an appropriate notion of traceability. Central to this characterization is a partial relativization of Demuth randomness, which may be more natural than the fully relativized version. We also show that an oracle is low for weak Demuth randomness if and only if it is computable.