An invariant for difference field extensions
Logic
2011-08-02 v4
Abstract
In this paper we introduce a new invariant (the distant degree) for difference field extensions of finite transcendence degree, and we explore some of its properties. We also discuss a generalisation of this invariant and of the limit degree to groups with an automorphism.
Keywords
Cite
@article{arxiv.0902.0844,
title = {An invariant for difference field extensions},
author = {Zoé Chatzidakis and Ehud Hrushovski},
journal= {arXiv preprint arXiv:0902.0844},
year = {2011}
}
Comments
After posting the previous version, we discovered the work of Willis on totally disconnected locally compact groups. Over a large area of overlap, our "distant degree" invariant of an automorphism agrees with Willis' {\em scale}. In the new version we describe the relations between the two frameworks. 14pp. July 2011: Small changes