English

Limit Models in Strictly Stable Abstract Elementary Classes

Logic 2024-09-12 v6

Abstract

In this paper, we examine the locality condition for non-splitting and determine the level of uniqueness of limit models that can be recovered in some stable, but not superstable, abstract elementary classes. In particular we prove (note that no tameness is assumed): Suppose that K\mathcal{K} is an abstract elementary class satisfying 1. the joint embedding and amalgamation properties with no maximal model of cardinality μ\mu. 2. stability in μ\mu. 3. κμ(K)<μ+\kappa^*_\mu(\mathcal{K})<\mu^+. 4. continuity for non-μ\mu-splitting (i.e. if pga-S(M)p\in\text{ga-S}(M) and MM is a limit model witnessed by Mii<α\langle M_i\mid i<\alpha\rangle for some limit ordinal α<μ+\alpha<\mu^+ and there exists NM0N \prec M_0 so that pMip\restriction M_i does not μ\mu-split over NN for all i<αi<\alpha, then pp does not μ\mu-split over NN). For θ\theta and δ\delta limit ordinals <μ+<\mu^+ both with cofinality κμ(K)\geq\kappa^*_\mu(\mathcal{K}), if K\mathcal{K} satisfies symmetry for non-μ\mu-splitting (or just (μ,δ)(\mu,\delta)-symmetry), then, for any M1M_1 and M2M_2 that are (μ,θ)(\mu,\theta) and (μ,δ)(\mu,\delta)-limit models over M0M_0, respectively, we have that M1M_1 and M2M_2 are isomorphic over M0M_0.

Keywords

Cite

@article{arxiv.1508.04717,
  title  = {Limit Models in Strictly Stable Abstract Elementary Classes},
  author = {Will Boney and Monica M. VanDieren},
  journal= {arXiv preprint arXiv:1508.04717},
  year   = {2024}
}

Comments

This article generalizes some results from arXiv:1507.01990

R2 v1 2026-06-22T10:37:13.450Z