English

The typical Turing degree

Logic 2011-11-07 v1

Abstract

The Turing degree of a real measures the computational difficulty of producing its binary expansion. Since Turing degrees are tailsets, it follows from Kolmogorov's 0-1 law that for any property which may or may not be satisfied by any given Turing degree, the satisfying class will either be of Lebesgue measure 0 or 1, so long as it is measurable. So either the \emph{typical} degree satisfies the property, or else the typical degree satisfies its negation. Further, there is then some level of randomness sufficient to ensure typicality in this regard. A similar analysis can be made in terms of Baire category, where a standard form of genericity now plays the role that randomness plays in the context of measure. We describe and prove a number of results in a programme of research which aims to establish the properties of the typical Turing degree, where typicality is gauged either in terms of Lebesgue measure or Baire category.

Keywords

Cite

@article{arxiv.1111.1064,
  title  = {The typical Turing degree},
  author = {George Barmpalias and Adam R. Day and Andrew E. M. Lewis},
  journal= {arXiv preprint arXiv:1111.1064},
  year   = {2011}
}

Comments

42 pages

R2 v1 2026-06-21T19:30:53.472Z