DEEP Π CLASSES.

A set of infinite binary sequences C ⊆ 2 is negligible if there is no partial probabilistic algorithm that produces an element of this set with positive probability. The study of negligibility is of particular interest in the context of Π classes. In this paper, we introduce the notion of depth for...

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Published in:Bulletin of Symbolic Logic Vol. 22; no. 2; pp. 249 - 287
Main Authors: BIENVENU, LAURENT, PORTER, CHRISTOPHER P.
Format: Article
Published: Cambridge University Press Jun2016
Subjects:
Online Access:View this record in EBSCOhost
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        10.1017/bsl.2016.9
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      tig:
        atl: DEEP Π CLASSES.
      aug:
        au:
          BIENVENU, LAURENT
          PORTER, CHRISTOPHER P.
        affil:
          LABORATOIRE CNRS J.-V. PONCELET 119002, BOLSHOY VLASYEVSKIY PEREULOK 11 MOSCOW, RUSSIA
          DEPARTMENT OF MATHEMATICS UNIVERSITY OF FLORIDA GAINESVILLE, FLORIDA 32611- 8105, USA
      su:
        Binary sequences
        Algorithms
        Probability theory
        Computable functions
        Algorithmic randomness
      sug:
        subj:
          Binary sequences
          Algorithms
          Probability theory
          Computable functions
          Algorithmic randomness
      keyword:
        Π10 classes
        algorithmic randomness
        computability theory
        probabilistic computation
      ab: A set of infinite binary sequences C ⊆ 2 is negligible if there is no partial probabilistic algorithm that produces an element of this set with positive probability. The study of negligibility is of particular interest in the context of Π classes. In this paper, we introduce the notion of depth for Π classes, which is a stronger form of negligibility. Whereas a negligible Π class C has the property that one cannot probabilistically compute a member of C with positive probability, a deep Π class C has the property that one cannot probabilistically compute an initial segment of a member of C with high probability. That is, the probability of computing a length n initial segment of a deep Π class converges to 0 effectively in n. We prove a number of basic results about depth, negligibility, and a variant of negligibility that we call tt-negligibility. We provide a number of examples of deep Π classes that occur naturally in computability theory and algorithmic randomness. We also study deep classes in the context of mass problems, examine the relationship between deep classes and certain lowness notions in algorithmic randomness, and establish a relationship between members of deep classes and the amount of mutual information with Chaitin's Ω.
      pubtype: Academic Journal
      doctype: Article
      src: R
    language: English
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