Examples of non-locality

by Baldwin and Shelah. [BlSh:862]
J Symbolic Logic, 2008
We use kappa-free but not Whitehead Abelian groups to construct abstract elementary classes which satisfy the amalgamation property but fail various conditions on the locality of types. We show in fact that in a large class of cases amalgamation can have no positive effect on locality by exhibiting a transformation of aec's which preserves non-locality but takes any aec satisfying a new property called admitting closures to one with amalgamation.

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