Abstract
We investigate the categoricity and number of non-isomorphic models in ℵ1 of sentences in\(L_{\omega _1 ,\omega } (Q)\). AssumingV=L we prove that no sentence in\(L_{\omega _1 ,\omega } (Q)\) has exactly one uncountable model. Thus partially answering problem 24 of a problem list by Friedman.
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Shelah, S. Categoricity in ℵ1 of sentences in\(L_{\omega _1 ,\omega } (Q)\) . Israel J. Math. 20, 127–148 (1975). https://doi.org/10.1007/BF02757882
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DOI: https://doi.org/10.1007/BF02757882