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External definability and groups in NIPĚ theories
- Source :
- Journal of the London Mathematical Society; vol 90, iss 1, 213-240; 0024-6107
- Publication Year :
- 2014
-
Abstract
- We prove that many properties and invariants of definable groups in NIP theories (i.e. theories without the independence property), such as definable amenability, G/G^{00}, etc., are preserved when passing to the theory of the Shelah expansion by externally definable sets, M^{\operatorname {ext} }, of a model M. In the light of these results, we continue the study of the 'definable topological dynamics' of groups in \operatorname {NIP} theories. In particular, we prove the Ellis group conjecture relating the Ellis group to G/G^{00} in some new cases, including definably amenable groups in o-minimal structures. © 2014 London Mathematical Society.
Details
- Database :
- OAIster
- Journal :
- Journal of the London Mathematical Society; vol 90, iss 1, 213-240; 0024-6107
- Notes :
- application/pdf, Journal of the London Mathematical Society vol 90, iss 1, 213-240 0024-6107
- Publication Type :
- Electronic Resource
- Accession number :
- edsoai.on1287415532
- Document Type :
- Electronic Resource