Abstract

We continue our study of finitary abstract elementary classes, defined in [7]. In this paper, we prove a categoricity transfer theorem for a case of simple finitary AECs. We introduce the concepts of weak κ-categoricity and f-primary models to the framework of א₀-stable simple finitary AECs with the extension property, whereby we gain the following theorem: Let (������, ≼ ������ ) be a simple finitary AEC, weakly categorical in some uncountable κ. Then (������, ≼ ������ ) is weakly categorical in each λ ≥ min { \group{ \{\kappa,\beth_{ \group{ (2^{ \aleph_{ 0 _} ^});^{ + ^} \group} _}\}; \group} . If the class (������, ≼ ������ ) is also LS(������)-tame, weak κ-categoricity is equivalent with κ-categoricity in the usual sense. We also discuss the relation between finitary AECs and some other non-elementary frameworks and give several examples