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Categoricity and Universal Classes. (arXiv:1712.08532v1 [math.LO])
来源于:arXiv
Let $(\mathcal{K} ,\subseteq )$ be a universal class with
$LS(\mathcal{K})=\lambda$ categorical in regular $\kappa >\lambda^+$ with
arbitrarily large models, and let $\mathcal{K}^*$ be the class of all
$\mathcal{A}\in\mathcal{K}_{>\lambda}$ for which there is $\mathcal{B} \in
\mathcal{K}_{\ge\kappa}$ such that $\mathcal{A}\subseteq\mathcal{B}$. We prove
that $\mathcal{K}^*$ is categorical in every $\xi >\lambda^+$,
$\mathcal{K}_{\ge\beth_{(2^{\lambda^+})^+}} \subseteq \mathcal{K}^{*}$, and the
models of $\mathcal{K}^*_{>\lambda^+}$ are essentially vector spaces (or
trivial i.e. disintegrated). 查看全文>>