Large-cardinal dichotomy for abstract elementary classes

Let k{\mathfrak k} be an abstract elementary class. Large-cardinal dichotomy conjecture. For a closed unbounded class CC of cardinals, the alternatives stated in the source should hold: (1) the promised conclusion of Theorem 28 can be obtained with CC an end segment of {μ:μ=1,μ}\{\mu:\mu=\beth_{1,\mu}\}, or with C={μ:μ=2,μ}C=\{\mu:\mu=\beth_{2,\mu}\}; and (2) for every such k{\mathfrak k}, either

MKλkλCcf(λ)=0Υλor[kM],M\in K^{\mathfrak k}_\lambda\wedge\lambda\in C\wedge {\rm cf}(\lambda)=\aleph_0\Rightarrow \Upsilon^{\rm or}_\lambda[\mathfrak k_M]\neq\emptyset,

or

λCcf(λ)=0I˙(λ,Kk)2λ (or at least λ+).\lambda\in C\wedge {\rm cf}(\lambda)=\aleph_0\Rightarrow \dot I(\lambda,K_{\mathfrak k})\geq 2^\lambda\text{ (or at least }\lambda^+\text{)}.

The source says that part (1) is intended for a continuation; the claims are therefore unresolved.

Sources & referencesView supporting material

Primary source

Saharon Shelah, “A.E.C. with not too many models”, arXiv:1302.4841 (2013).

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