Let U be a monster model and let D be a subset of U. Let (U,D) denote theexpansion of U with a new predicate for D. Write e(D) for the collection of all subsets C of U such that (U,C) is elementary equivalent to (U,D). We prove that if e(D) has finite VC-dimension then D is externally definable (i.e. it is the trace on U of a set definable in an elementary superstructure of U).

Elementary classes of finite VC-dimension

ZAMBELLA, Domenico
2015-01-01

Abstract

Let U be a monster model and let D be a subset of U. Let (U,D) denote theexpansion of U with a new predicate for D. Write e(D) for the collection of all subsets C of U such that (U,C) is elementary equivalent to (U,D). We prove that if e(D) has finite VC-dimension then D is externally definable (i.e. it is the trace on U of a set definable in an elementary superstructure of U).
2015
54
5-6
511
520
http://arxiv.org/abs/1412.5781
http://link.springer.com/article/10.1007%2Fs00153-015-0424-0
VC-dimension; NIP; Externally definable sets; Expansions of saturated models; MSC classes: 03C95
Zambella, Domenico
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1507574
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