
arXiv: 1607.03376
We investigate how a C*-algebra could consist of functions on a noncommutative set: a discretization of a C*-algebra $A$ is a $*$-homomorphism $A \to M$ that factors through the canonical inclusion $C(X) \subseteq \ell^\infty(X)$ when restricted to a commutative C*-subalgebra. Any C*-algebra admits an injective but nonfunctorial discretization, as well as a possibly noninjective functorial discretization, where $M$ is a C*-algebra. Any subhomogenous C*-algebra admits an injective functorial discretization, where $M$ is a W*-algebra. However, any functorial discretization, where $M$ is an AW*-algebra, must trivialize $A = B(H)$ for any infinite-dimensional Hilbert space $H$.
16 pages. This paper supersedes arXiv:1412.1721
function algebra, 46M15, noncommutative set, General Mathematics, diffuse measure, Mathematics - Operator Algebras, 46L85, 46M15 (Primary), 46L30 (Secondary), math.FA, Noncommutative topology, Pure Mathematics, discrete space, Functional Analysis (math.FA), Mathematics - Functional Analysis, pure state, FOS: Mathematics, 46L85, 46L30, profinite completion, spectrum obstruction, Operator Algebras (math.OA), math.OA, 46M15 (Primary)
function algebra, 46M15, noncommutative set, General Mathematics, diffuse measure, Mathematics - Operator Algebras, 46L85, 46M15 (Primary), 46L30 (Secondary), math.FA, Noncommutative topology, Pure Mathematics, discrete space, Functional Analysis (math.FA), Mathematics - Functional Analysis, pure state, FOS: Mathematics, 46L85, 46L30, profinite completion, spectrum obstruction, Operator Algebras (math.OA), math.OA, 46M15 (Primary)
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