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arXiv · 2609.08892

The hyperfinite II_1 factor is not quasidiagonal

Narutaka Ozawa
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Abstract

We construct an MF C*-algebra A such that the spatial tensor product of A and the hyperfinite II_1 factor R contains a proper isometry. Consequently, stable finiteness of C*-algebras is not stable under tensor product and the hyperfinite II_1 factor is not a quasidiagonal C*-algebra. The C*-algebra A is non-simple and has only non-faithful tracial states. This result was obtained using OpenAI's Chat GPT Pro 6.0.

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Narutaka Ozawa. 2026-09-08. The hyperfinite II_1 factor is not quasidiagonal. https://arxiv.org/abs/2609.08892

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