On the number of countable models of stable theories (Q2759151)

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scientific article; zbMATH DE number 1680984
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On the number of countable models of stable theories
scientific article; zbMATH DE number 1680984

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    On the number of countable models of stable theories (English)
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    11 December 2001
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    stability
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    independence
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    isomorphism classes
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    countable model
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    nonisolated type
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    definable elements
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    The aim of the paper is to prove that the number \(I(T,\aleph_0)\) of isomorphism classes of countable models of a countable, complete, stable, first-order theory having infinite models fulfills the condition \(I(T,\aleph_0)\geq \aleph_0\). In order to do so the author proves the fact that the condition above follows by the existence of a stationary, strongly nonisolated type over \(\emptyset\). Then the statement above is a consequence of the Lemma: Supposing that \(p\in S_1(\emptyset)\) is an accumulation point of types of definable elements one obtains that \(p\) is stationary and strongly nonisolated.
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