English

Large transitive models in local {\rm ZFC}

Logic 2023-03-28 v1

Abstract

This paper is a sequel to \cite{Tz10}, where a local version of ZFC, LZFC, was introduced and examined and transitive models of ZFC with properties that resemble large cardinal properties, namely Mahlo and Π11\Pi_1^1-indescribable models, were considered. By analogy we refer to such models as "large models", and the properties in question as "large model properties". Continuing here in the same spirit we consider further large model properties, that resemble stronger large cardinals, namely, "elementarily embeddable", "extendible" and "strongly extendible", "critical" and "strongly critical", "self-critical'' and "strongly self-critical", the definitions of which involve elementary embeddings. Each large model property ϕ\phi gives rise to a localization axiom Locϕ(ZFC)Loc^{\phi}({\rm ZFC}) saying that every set belongs to a transitive model of ZFC satisfying ϕ\phi. The theories LZFCϕ=LZFC{\rm LZFC}^\phi={\rm LZFC}+Locϕ(ZFC)Loc^{\phi}({\rm ZFC}) are local analogues of the theories ZFC+"there is a proper class of large cardinals ψ\psi", where ψ\psi is a large cardinal property. If sext(x)sext(x) is the property of strong extendibility, it is shown that LZFCsext{\rm LZFC}^{sext} proves Powerset and Σ1\Sigma_1-Collection. In order to refute V=LV=L over LZFC, we combine the existence of strongly critical models with an axiom of different flavor, the Tall Model Axiom (TMATMA). V=LV=L can also be refuted by TMATMA plus the axiom GCGC saying that "there is a greatest cardinal", although it is not known if TMA+GCTMA+GC is consistent over LZFC. Finally Vop\v{e}nka's Principle (VPVP) and its impact on LZFC are examined. It is shown that LZFCsext+VP{\rm LZFC}^{sext}+VP proves Powerset and Replacement, i.e., ZFC is fully recovered. The same is true for some weaker variants of LZFCsext{\rm LZFC}^{sext}. Moreover the theories LZFCsext^{sext}+VPVP and ZFC+VPVP are shown to be identical.

Cite

@article{arxiv.2303.15287,
  title  = {Large transitive models in local {\rm ZFC}},
  author = {Athanassios Tzouvaras},
  journal= {arXiv preprint arXiv:2303.15287},
  year   = {2023}
}

Comments

32 pages

R2 v1 2026-06-28T09:35:50.295Z