English

Iterated failures of choice

Logic 2021-07-26 v3

Abstract

We combine several folklore observations to provide a working framework for iterating constructions which contradict the axiom of choice. We use this to define a model in which any kind of structural failure must fail with a proper class of counterexamples. For example, the rational numbers have a proper class of non-isomorphic algebraic closures, every partial order embeds into the cardinals of the model, every set is the image of a Dedekind-finite set, every weak choice axiom of the form ACXY\mathsf{AC}_X^Y fails with a proper class of counterexamples, every field has a vector space with two linearly independent vectors but without endomorphisms that are not scalar multiplication, etc.

Keywords

Cite

@article{arxiv.1911.09285,
  title  = {Iterated failures of choice},
  author = {Asaf Karagila},
  journal= {arXiv preprint arXiv:1911.09285},
  year   = {2021}
}

Comments

Complete rewrite of the paper; 22 pages

R2 v1 2026-06-23T12:23:00.557Z