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Bibliographic Details
Main Authors: Gao, David, Jekel, David
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2512.10129
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Table of Contents:
  • We show that there are $\mathrm{II}_1$ factors $M$ and elementary embeddings $M \to M^{\mathcal{U}}$ which do not lift to sequences of UCP maps, and in fact $M$ 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 $M^{\mathcal{U}}$ of a separable $\mathrm{II}_1$ factor do not lift to a sequence of UCP maps $φ_n: M \to M$.