Submission date: 22 August 2015.

Abstract:

Let M = (M, <, +, ...) be a weakly o-minimal expansion of an ordered group. This paper has two parts. In the first part, we introduce the notion of M having no external limits and use it to prove that a large collection of non-valuational structures M do not admit definable Skolem functions. In the second part, we provide an alternative characterization of the canonical o-minimal completion from Wencel and employ it to produce new examples of non-valuational structures.

Mathematics Subject Classification: 03C64

Keywords and phrases:

Full text arXiv 1508.05492: pdf, ps.