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arXiv · 2506.11983

Embeddings into the ultrapower of the Jiang-Su algebra

Ben Bouwen·Jennifer Pi
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Abstract

We study existence of embeddings into ultrapowers of the Jiang-Su algebra $\mathcal{Z}$ and the Razak-Jacelon algebra $\mathcal{W}$. More specifically, we show that the cone over any separable $C^*$-algebra embeds into the ultrapowers of both $\mathcal{Z}$ and $\mathcal{W}$. We also show that the result for $\mathcal{Z}$ generalizes to separable and exact continuous fields of $C^*$-algebras for which one of the fibers embeds into the ultrapower of $\mathcal{Z}$, if this fiber is suitably well-behaved.

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Ben Bouwen, Jennifer Pi. 2025-06-13. Embeddings into the ultrapower of the Jiang-Su algebra. https://arxiv.org/abs/2506.11983

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