English

Good Frames in the Hart-Shelah Example

Logic 2018-07-26 v4

Abstract

For a fixed natural number n1n \geq 1, the Hart-Shelah example is an abstract elementary class (AEC) with amalgamation that is categorical exactly in the infinite cardinals less than or equal to n\aleph_n. We investigate recently-isolated properties of AECs in the setting of this example. We isolate the exact amount of type-shortness holding in the example and show that it has a type-full good n1\aleph_{n-1}-frame which fails the existence property for uniqueness triples. This gives the first example of such a frame. Along the way, we develop new tools to build and analyze good frames.

Cite

@article{arxiv.1607.03885,
  title  = {Good Frames in the Hart-Shelah Example},
  author = {Will Boney and Sebastien Vasey},
  journal= {arXiv preprint arXiv:1607.03885},
  year   = {2018}
}

Comments

24 pages

R2 v1 2026-06-22T14:53:56.073Z