Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Noncommutative Cartan C*-subalgebras   We characterise Exel's noncommutative Cartan subalgebras in several ways
using uniqueness of conditional expectations, relative commutants, or purely
outer inverse semigroup actions. We describe in which sense the crossed product
decomposition for a noncommutative Cartan subalgebra is unique. We relate the
property of being a noncommutative Cartan subalgebra to aperiodic inclusions
and effectivity of dual groupoids. In particular, we extend Renault's
characterisation of commutative Cartan subalgebras.

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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: cs
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an