The Unique Limit Model Conjecture for dependent theories

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Let TT be dependent, let ∣T∣<λ=λ<λ|T|<\lambda=\lambda^{<\lambda}, let λ+=2λ\lambda^+=2^\lambda, and let σ=cf⁡(σ)<λ\sigma=\operatorname{cf}(\sigma)<\lambda. Suppose ⟨Mα:α<λ+⟩\langle M_\alpha:\alpha<\lambda^+\rangle is an increasing continuous sequence of models of cardinality λ\lambda whose union is λ+\lambda^+-saturated. The Unique Limit Model Conjecture. There is a club E⊆λ+E\subseteq\lambda^+ such that all models MαM_\alpha with α∈E\alpha\in E and cf⁡(α)=σ\operatorname{cf}(\alpha)=\sigma are pairwise isomorphic. This predicts uniqueness, on a club of stages of fixed cofinality, for limit models arising in dependent theories; the source supplies no resolution in the displayed passage.

References

Primary source

Saharon Shelah, “Dependent dreams: recounting types”, arXiv:1202.5795 (2012).

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