Hannes Thiel

activity

20232025

collaborators

5 papers

math.OA2025

Distance to regular elements and polar decompositions in a C*-algebra

Hannes Thiel

We show that the distance from an element of a C*-algebra to the set of regular elements is the infimum of the $δ > 0$ for which the $δ$ -cut-down of the element admits a polar decomp…

math.OA2024

Lie ideals in properly infinite C*-algebras

Hannes Thiel

We show that every Lie ideal in a unital, properly infinite C*-algebra is commutator equivalent to a unique two-sided ideal. It follows that the Lie ideal structure of such a C*-al…

math.OA2024

The ideal separation property for reduced group $C^{*}$ -algebras

Are Austad, Hannes Thiel

We say that an inclusion of an algebra $A$ into a $C^{*}$ -algebra $B$ has the ideal separation property if closed ideals in $B$ can be recovered by their intersection with $A$ . Such…

math.OA2024

Real rank of some multiplier algebras

Hannes Thiel

We show that there exists a separable, nuclear C*-algebra with real rank zero and trivial K-theory such that its multiplier and corona algebra have real rank one. This disproves tw…

math.OA2023

Real rank of extensions of C*-algebras

Hannes Thiel

Given a closed ideal $I$ in a C*-algebra $A$ , we develop techniques to bound the real rank of $A$ in terms of the real ranks of $I$ and $A / I$ . Building on work of Brown, Lin and Zh…

Distance to regular elements and polar decompositions in a C*-algebra

Lie ideals in properly infinite C*-algebras

The ideal separation property for reduced group C∗-algebras

Real rank of some multiplier algebras

Real rank of extensions of C*-algebras

The ideal separation property for reduced group $C^{*}$ -algebras