Hostname: page-component-76d6cb85b7-7262s Total loading time: 0 Render date: 2026-07-18T02:16:56.750Z Has data issue: false hasContentIssue false

The Complexity of Orbits of Computably Enumerable Sets

Published online by Cambridge University Press:  15 January 2014

Peter A. Cholak
Affiliation:
Department of Mathematics, University of Notre Dame, Notre Dame, IN 46556-5683, USA E-mail: Peter.Cholak.1@nd.edu URL: http://www.nd.edu/~cholak
Rodney Downey
Affiliation:
School of Mathematics, Statistics and Computer Science, Victoria University, P.O. BOX 600, Wellington, New Zealand E-mail: Rod.Downey@vuw.ac.nz , URL: http://www.mcs.vuw.ac.nz/~downey
Leo A. Harrington
Affiliation:
Department of Mathematics, University of California, Berkeley, CA 94720-3840, USA E-mail: leo@math.berkeley.edu

Abstract

The goal of this paper is to announce there is a single orbit of the c.e. sets with inclusion, ε, such that the question of membership in this orbit is complete. This result and proof have a number of nice corollaries: the Scott rank of ε is + 1; not all orbits are elementarily definable; there is no arithmetic description of all orbits of ε; for all finite α ≥ 9, there is a properly orbit (from the proof).

Information

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable