Hanf numbers via accessible images

We present several new model-theoretic applications of the fact that, under the assumption that there exists a proper class of almost strongly compact cardinals, the powerful image of any accessible functor is accessible. In particular, we generalize to the context of accessible categories the recen...

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Bibliographic Details
Main Authors: Michael Lieberman, Jiri Rosicky
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2017-06-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/2190/pdf
Description
Summary:We present several new model-theoretic applications of the fact that, under the assumption that there exists a proper class of almost strongly compact cardinals, the powerful image of any accessible functor is accessible. In particular, we generalize to the context of accessible categories the recent Hanf number computations of Baldwin and Boney, namely that in an abstract elementary class (AEC) if the joint embedding and amalgamation properties hold for models of size up to a sufficiently large cardinal, then they hold for models of arbitrary size. Moreover, we prove that, under the above-mentioned large cardinal assumption, every metric AEC is strongly d-tame, strengthening a result of Boney and Zambrano and pointing the way to further generalizations.
ISSN:1860-5974