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This article is cited in 4 scientific papers (total in 5 papers)
Definability of 1-Types in Weakly $o$-Minimal Theories
B. S. Baizhanov Institute for Problems of Informatics and Control Sciences
Abstract:
In the article, we prove a criterion for definability of 1-types over sets in weakly $o$-minimal theories in terms of left and right convergences of a formula to a type.
Van den Dries proved that every type over the field of reals is definable. Marker and Steinhorn strengthened his result. They (and, later, Pillay) proved the following assertion. Let $M\prec N$ be a pair of models of some $o$-minimal theory. If, for each element of $N$, the type of this element over $M$ is definable then, for each tuple of elements of $N$, the type of this tuple over $M$ is definable.
We construct a weakly $o$-minimal theory for which the Marker–Steinhorn theorem fails; i. e., some pair of models of the theory possesses the following property: For all elements of the larger model, the 1-type
over the smaller model is definable but there exists a tuple of elements of the larger model whose 2-type over the smaller model is not definable.
Key words:
definable type, weakly $o$-minimal theory, nonorthogonality of types.
Received: 19.02.2004
Citation:
B. S. Baizhanov, “Definability of 1-Types in Weakly $o$-Minimal Theories”, Mat. Tr., 8:2 (2005), 3–38; Siberian Adv. Math., 16:2 (2006), 1–33
Linking options:
https://www.mathnet.ru/eng/mt60 https://www.mathnet.ru/eng/mt/v8/i2/p3
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Abstract page: | 419 | Full-text PDF : | 153 | References: | 52 | First page: | 1 |
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