Submission date: 3 April 2015.

Abstract:

We study definably amenable groups in NIP theories, and answer a question of Newelski (and also of Chernikov-Simon), by giving an example in the o-minimal context where weak generic types do not coincide with almost periodic types, equivalently where the union of the minimal subflows of suitable type spaces is not closed. We give other positive results in this o-minimal context.

Mathematics Subject Classification: 03C64, 54H20

Keywords and phrases:

Full text arXiv 1504.00875: pdf, ps.