Covering Dimension of C*-Algebras and 2-Coloured Classification

Joan Bosa, Nathanial P. Brown, Yasuhiko Sato, Aaron Peter Tikuisis, Stuart White, Wilhelm Winter

Research output: Working paper


We introduce the concept of finitely coloured equivalence for unital *-homomorphisms between C*-algebras, for which unitary equivalence is the 1-coloured case. We use this notion to classify *-homomorphisms from separable, unital, nuclear C*-algebras into ultrapowers of simple, unital, nuclear, Z-stable C*-algebras with compact extremal trace space up to 2-coloured equivalence by their behaviour on traces; this is based on a 1-coloured classification theorem for certain order zero maps, also in terms of tracial data.
As an application we calculate the nuclear dimension of non-AF, simple, separable, unital, nuclear, Z-stable C*-algebras with compact extremal trace space: it is 1. In the case that the extremal trace space also has finite topological covering dimension, this confirms the remaining open implication of the Toms-Winter conjecture. Inspired by homotopy-rigidity theorems in geometry and topology, we derive a "homotopy equivalence implies isomorphism" result for large classes of C*-algebras with finite nuclear dimension.
Original languageEnglish
Number of pages93
Publication statusPublished - 24 May 2016

Bibliographical note

arXiv:1506.03974 [math.OA]


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