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arXiv · 2610.09314

The Type $ω$-Vaught's Conjecture for $ω$-stable Theories

Hongyu Zhu
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Abstract

We propose a new variant of Vaught's conjecture, based on Martin's (model-theoretic) conjecture and the $ω$-Vaught's conjecture of Gonzalez and Montalbán. For $ω$-stable theories, we prove the conjecture by analyzing in detail Bouscaren's and Shelah-Harrington-Makkai's proofs of Martin's conjecture and Vaught's conjecture, respectively, for $ω$-stable theories. In particular, when there are countably many countable models, we improve the required number of quantifiers for a Scott sentence from $ω+ω$ to $ω+5$, and we obtain a similar bound of $ω+6$ for the uncountable case.

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Hongyu Zhu. 2026-10-07. The Type $ω$-Vaught's Conjecture for $ω$-stable Theories. https://arxiv.org/abs/2610.09314

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