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Closure of tensor products in the σ-C*-algebra category

Determine whether either the minimal or maximal C*-algebraic tensor product of two σ-C*-algebras yields a σ-C*-algebra, thereby ensuring functoriality of these tensor products in the σ-C*-algebra setting.

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Background

Defining a symmetric monoidal structure on categories of σ-C*-algebras requires that tensor products of σ-C*-algebras remain inside the category. This closure is unclear for both minimal and maximal tensor products and impacts functoriality and monoidal structures in the noncommutative measurable setting.

References

The first problem that arises with this is that it is unclear whether either tensor product of two s can be guaranteed to be a again.

Categories of abstract and noncommutative measurable spaces (2504.13708 - Fritz et al., 18 Apr 2025) in Introduction, Overview (Tensor products of σ-C*-algebras)