Zobrazeno 1 - 10
of 68
pro vyhledávání: '"Christensen, Johannes"'
Given a Hausdorff locally compact \'etale groupoid $\mathcal G$, we describe as a topological space the part of the primitive spectrum of $C^*(\mathcal G)$ obtained by inducing one-dimensional representations of amenable isotropy groups of $\mathcal
Externí odkaz:
http://arxiv.org/abs/2405.02025
Given a locally compact \'etale groupoid and an ideal $I$ in its groupoid C$^*$-algebra, we show that $I$ defines a family of ideals in group C$^*$-algebras of the isotropy groups and then study to which extent $I$ is determined by this family. As an
Externí odkaz:
http://arxiv.org/abs/2308.10768
Autor:
Christensen, Johannes
We describe two kinds of regular invariant measures on the boundary path space of a second countable topological graph, which allows us to describe all extremal tracial weights on the graph C$^{*}$-algebra which are not gauge-invariant. Using this de
Externí odkaz:
http://arxiv.org/abs/2208.12122
Publikováno v:
In Advances in Mathematics June 2024 447
Autor:
Christensen, Johannes, Vaes, Stefaan
Publikováno v:
Communications in Mathematical Physics 390 (2022), 1341-1367
Given a topologically free action of a countable group $G$ on a compact metric space $X$, there is a canonical correspondence between continuous 1-cocycles for this group action and diagonal 1-parameter groups of automorphisms of the reduced crossed
Externí odkaz:
http://arxiv.org/abs/2104.13890
Motivated by the problem of characterizing KMS states on the reduced C$^*$-algebras of \'etale groupoids, we show that the reduced norm on these algebras induces a C$^*$-norm on the group algebras of the isotropy groups. This C$^*$-norm coincides wit
Externí odkaz:
http://arxiv.org/abs/2012.11446
Autor:
Christensen, Johannes, Thomsen, Klaus
We provide a general description of the KMS states for flows whose fixed point algebra satisfies a certain regularity condition. This is the applied to crossed products by discrete groups, and in particular to certain flows on crossed products by dis
Externí odkaz:
http://arxiv.org/abs/2006.14443
Autor:
Christensen, Johannes, Thomsen, Klaus
A classical construction associates to a transient random walk on a discrete group $\Gamma$ a compact $\Gamma$-space $\partial_M \Gamma$ known as the Martin boundary. The resulting crossed product $C^*$-algebra $C(\partial_M \Gamma) \rtimes_r \Gamma$
Externí odkaz:
http://arxiv.org/abs/2006.14433
Autor:
Christensen, Johannes
We generalise a number of classical results from the theory of KMS states to KMS weights in the setting of $C^{*}$-dynamical systems arising from a continuous groupoid homomorphism $c:\mathcal{G} \to \mathbb{R}$ on a locally compact second countable
Externí odkaz:
http://arxiv.org/abs/2005.01792
Autor:
Christensen, Johannes, Thomsen, Klaus
Let $\varphi:X\to X$ be a homeomorphism of a compact metric space $X$. For any continuous function $F:X\to \mathbb{R}$ there is a one-parameter group $\alpha^{F}$ of automorphisms on the crossed product $C^*$-algebra $C(X)\rtimes_{\varphi}\mathbb{Z}$
Externí odkaz:
http://arxiv.org/abs/1912.06069