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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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
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author Michael Lieberman
Jiri Rosicky
author_facet Michael Lieberman
Jiri Rosicky
author_sort Michael Lieberman
collection DOAJ
description 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.
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spelling doaj.art-57cd71e664d64845aa526e0b5fca33ff2022-12-22T04:14:22ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742017-06-01Volume 13, Issue 210.23638/LMCS-13(2:11)20172190Hanf numbers via accessible imagesMichael LiebermanJiri RosickyWe 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.https://lmcs.episciences.org/2190/pdfmathematics - logicmathematics - category theory03c95, 03c52, 18c35, 03e55
spellingShingle Michael Lieberman
Jiri Rosicky
Hanf numbers via accessible images
Logical Methods in Computer Science
mathematics - logic
mathematics - category theory
03c95, 03c52, 18c35, 03e55
title Hanf numbers via accessible images
title_full Hanf numbers via accessible images
title_fullStr Hanf numbers via accessible images
title_full_unstemmed Hanf numbers via accessible images
title_short Hanf numbers via accessible images
title_sort hanf numbers via accessible images
topic mathematics - logic
mathematics - category theory
03c95, 03c52, 18c35, 03e55
url https://lmcs.episciences.org/2190/pdf
work_keys_str_mv AT michaellieberman hanfnumbersviaaccessibleimages
AT jirirosicky hanfnumbersviaaccessibleimages