Examples of Non-Locality
Baldwin, John T.
PublisherAssociation for Symbolic Logic
MetadataShow full item record
We use kappa-free but not Whitehead Abelian groups to construct Abstract Elementary Classes (AEC) which satisfy the amalgamation property but fail various conditions on the locality of Galois-types. We introduce the notion that an AEC admits intersections. We conclude that for AEC which admit intersections. the amalgamation property can have no positive effect on locality: there is a transformation of AEC's which preserves non-locality but takes any AEC which admits intersections to one with amalgamation. More specifically we have: Theorem 5.3. There is an AEC with amalgamation which is not (N-0. N-1)-tame but is (2(N0), infinity)-tame: Theorem 3.3. It is consistent with ZFC that there is an AEC with amalgamation which is not (<= N-2, <= N-2)-compact.