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On PAC and bounded substructures of a stable structure

Published online by Cambridge University Press:  12 March 2014

Anand Pillay
Affiliation:
School of Mathematics, University of Leeds, Leeds LS2 9JT, UK. E-mail: [email protected]
Dominika Polkowska
Affiliation:
St. Cecilia Novitiate, 801 Dominion Drive, Nashville, TN 37228, USA

Abstract

We introduce and study the notions of a PAC-substructure of a stable structure, and a bounded substructure of an arbitrary substructure, generalizing [10]. We give precise definitions and equivalences, saying what it means for properties such as PAC to be first order, study some examples (such as differentially closed fields) in detail, relate the material to generic automorphisms, and generalize a “descent theorem” for pseudo-algebraically closed fields to the stable context. We also point out that the elementary invariants of pseudo-algebraically closed fields from [6] are also valid for pseudo-differentially closed fields.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 2006

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