Elementary embeddings into ultrapower $\mathrm{II}_1$ factors without a UCP lift
Operator Algebras
2025-12-12 v1 Logic
Abstract
We show that there are factors and elementary embeddings which do not lift to sequences of UCP maps, and in fact can be chosen from any given elementary equivalence class. Furthermore, under continuum hypothesis, we show that in the sense of cardinality "most" automorphisms of a ultrapower of a separable factor do not lift to a sequence of UCP maps .
Cite
@article{arxiv.2512.10129,
title = {Elementary embeddings into ultrapower $\mathrm{II}_1$ factors without a UCP lift},
author = {David Gao and David Jekel},
journal= {arXiv preprint arXiv:2512.10129},
year = {2025}
}
Comments
8 pages. Comments welcome