3 papers
math.OA2025
K-theory of C*-algebras arising from commuting Hilbert bimodules and invariant ideals
Astrid an Huef, Abraham C. S. Ng, Aidan Sims
We study the K-theory of the Cuntz-Nica-Pimsner C*-algebra of a rank-two product system that is an extension determined by an invariant ideal of the coefficient algebra. We use a c…
math.OA2025
A twist over a minimal étale groupoid that is topologically nontrivial over the interior of the isotropy
Becky Armstrong, Abraham C. S. Ng, Aidan Sims +1
We present an example of a twist over a minimal Hausdorff étale groupoid such that the restriction of the twist to the interior of the isotropy is not topologically trivial; that…
math.OA2025
Nuclear dimension of extensions of commutative C*-algebras by Kirchberg algebras
Samuel Evington, Abraham C. S. Ng, Aidan Sims +1
We compute the nuclear dimension of extensions of C*-algebras involving commutative unital quotients and stable Kirchberg ideals. We identify the finite directed graphs whose C*-al…