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Preprint Number 1037

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1037. Sebastien Vasey
Saturation and solvability in abstract elementary classes with amalgamation

Submission date: 26 April 2016


Let K be an abstract elementary class (AEC) with amalgamation and no maximal models. Let λ > LS(K). If K is categorical in λ, then the model of cardinality λ is Galois-saturated.

This answers a question asked independently by Baldwin and Shelah. We deduce several corollaries: K has a unique limit model in each cardinal below λ, (when λ is big-enough) K is weakly tame below λ, and the thresholds of several existing categoricity transfers can be improved.
We also prove a downward transfer of solvability (a version of superstability introduced by Shelah):

Let K be an AEC with amalgamation and no maximal models. Let λ > μ > LS(K). If K is solvable in λ, then K is solvable in μ.

Mathematics Subject Classification: 03C48 (Primary), 03C45, 03C52, 03C55 (Secondary)

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Full text arXiv 1604.07743: pdf, ps.

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