On NIP and invariant measures
Journal of the European Mathematical Society, Tome 13 (2011) no. 4, pp. 1005-1061
We study forking, Lascar strong types, Keisler measures and definable groups, under an assumption of NIP (not the independence property), continuing aspects of the paper [16]. Among key results are (i) if p=tp(b/A) does not fork over A then the Lascar strong type of b over A coincides with the compact strong type of b over A and any global nonforking extension of p is Borel definable over bdd(A), (ii) analogous statements for Keisler measures and definable groups, including the fact that G000=G00 for G definably amenable, (iii) definitions, characterizations and properties of “generically stable” types and groups, (iv) uniqueness of invariant (under the group action) Keisler measures on groups with finitely satisfiable generics, (v) a proof of the compact domination conjecture for (definably compact) commutative groups in o-minimal expansions of real closed fields.
@article{JEMS_2011_13_4_a6,
author = {Ehud Hrushovski and Anand Pillay},
title = {On {NIP} and invariant measures},
journal = {Journal of the European Mathematical Society},
pages = {1005--1061},
year = {2011},
volume = {13},
number = {4},
doi = {10.4171/jems/274},
url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/274/}
}
Ehud Hrushovski; Anand Pillay. On NIP and invariant measures. Journal of the European Mathematical Society, Tome 13 (2011) no. 4, pp. 1005-1061. doi: 10.4171/jems/274
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