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Frobenius Algebras, Q-Systems and Modules

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Tensor Categories and Endomorphisms of von Neumann Algebras

Part of the book series: SpringerBriefs in Mathematical Physics ((BRIEFSMAPHY,volume 3))

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Abstract

We introduce the notion of Q-systems as Frobenius algebras in a C* tensor category, enjoying a standardness property. Q-systems in the category of endomorphisms of an infinite factor \(N\) completely characterize extensions \(N\subset M\). Modules and bimodules of Q-systems are equivalent to homomorphisms \(N\rightarrow M\) resp. \(M_1\rightarrow M_2\).

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Notes

  1. 1.

    The term factorial might be more appropriate in this context. “Simple”, however, is more in line with standard category terminology, cf. Corollary 3.40.

  2. 2.

    More precisely, \((\beta ,m^*)\) is a module and \((\beta ,m)\) is a co-module. We do not make the distinction because the dualization is canonically given by the operator adjoint.

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Correspondence to Marcel Bischoff .

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Bischoff, M., Kawahigashi, Y., Longo, R., Rehren, KH. (2015). Frobenius Algebras, Q-Systems and Modules. In: Tensor Categories and Endomorphisms of von Neumann Algebras. SpringerBriefs in Mathematical Physics, vol 3. Springer, Cham. https://doi.org/10.1007/978-3-319-14301-9_3

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