Non-embeddable II$_1$ factors resembling the hyperfinite II$_1$ factor

Isaac Goldbring

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arXiv · 2101.10467

Non-embeddable II$_1$ factors resembling the hyperfinite II$_1$ factor

Isaac Goldbring

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Abstract

We consider various statements that characterize the hyperfinite II$_1$ factors amongst embeddable II$_1$ factors in the non-embeddable situation. In particular, we show that "generically" a II$_1$ factor has the Jung property (which states that every embedding of itself into its ultrapower is unitarily conjugate to the diagonal embedding) if and only if it is self-tracially stable (which says that every such embedding has an approximate lifting). We prove that the enforceable factor, should it exist, has these equivalent properties. Our techniques are model-theoretic in nature. We also show how these techniques can be used to give new proofs that the hyperfinite II$_1$ factor has the aforementioned properties.

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Isaac Goldbring. 2021-01-25. Non-embeddable II$_1$ factors resembling the hyperfinite II$_1$ factor. https://arxiv.org/abs/2101.10467

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