English

Structures in Familiar Classes Which Have Scott Rank $\omega_1^{CK}$

Logic 2008-03-25 v1

Abstract

There are familiar examples of computable structures having various computable Scott ranks. There are also familiar structures, such as the Harrison ordering, which have Scott rank ω1CK+1\omega_1^{CK}+1. Makkai produced a structure of Scott rank ω1CK\omega_1^{CK}, which can be made computable, and simplified so that it is just a tree. In the present paper, we show that there are further computable structures of Scott rank ω1CK\omega_1^{CK} in the following classes: undirected graphs, fields of any characteristic, and linear orderings. The new examples share with the Harrison ordering, and the tree just mentioned, a strong approximability property.

Keywords

Cite

@article{arxiv.0803.3296,
  title  = {Structures in Familiar Classes Which Have Scott Rank $\omega_1^{CK}$},
  author = {Wesley Calvert and Sergey S. Goncharov and Julia F. Knight},
  journal= {arXiv preprint arXiv:0803.3296},
  year   = {2008}
}

Comments

Advances in Logic (Proceedings of the North Texas Logic Conference, October 8--10, 2004), Contemporary Mathematics 425 (2007), American Mathematical Society, 49--66

R2 v1 2026-06-21T10:23:44.829Z