Archive for Mathematical Logic

, Volume 41, Issue 1, pp 33–34 | Cite as

A note on the Σ1 spectrum of a theory

  • Michael Möllerfeld
  • Michael Rathjen


Let T be a suitable system of classical set theory. We will show, that the Σ1 spectrum of T, i.e. the set of ordinals having good Σ1 definition in T is an initial segment of the ordinals.


Initial Segment Suitable System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Michael Möllerfeld
    • 1
  • Michael Rathjen
    • 2
  1. 1.Institut für mathematische Logik und Grundlagenforschung, Westfälische Wilhelms-Universität, Einsteinstr. 62, 48149 Münster, Germany. e-mail: mimoe@math.uni-muenster.deDE
  2. 2.School of Mathematics, University of Leeds, Leeds LS2 9JT, UK. e-mail:

Personalised recommendations