9 citations · 72 across the 18 of their papers we have counts for
18 papers
Orthogonal Intertwiners for Infinite Particle Systems in The Continuum
Stefan Wagner
This article focuses on a system of sticky Brownian motions, also known as Howitt-Warren martingale problem, and correlated Brownian motions and shows that infinite-dimensional ort…
The noncommutative geometry of frame bundles
Stefan Wagner
We apply ourselves to the noncommutative geometry of frame bundles by showing that each C-algebraic noncommutative principal -bundle is, up to isomorphism, uniq…
Non-Abelian extensions of groupoids and their groupoid rings
Natã Machado, Johan Öinert, Stefan Wagner
We present a geometrically oriented classification theory for non-Abelian extensions of groupoids generalizing the classification theory for Abelian extensions of groupoids by West…
Intertwining and Duality for Consistent Markov Processes
Simone Floreani, Sabine Jansen, Frank Redig +1
In this paper we derive intertwining relations for a broad class of conservative particle systems both in discrete and continuous setting. Using the language of point process theor…
An Atiyah Sequence for Noncommutative Principal Bundles
Kay Schwieger, Stefan Wagner
We present a derivation-based Atiyah sequence for noncommutative principal bundles. Along the way we treat the problem of deciding when a given -automorphism on the quantum bas…
Prime group graded rings with applications to partial crossed products and Leavitt path algebras
Daniel Lännström, Patrik Lundström, Johan Öinert +1
In this article we generalize a classical result by Passman on primeness of unital strongly group graded rings to the class of nearly epsilon-strongly group graded rings which are…
Lifting spectral triples to noncommutative principal bundles
Kay Schwieger, Stefan Wagner
Given a free action of a compact Lie group on a unital C*-algebra and a spectral triple on the corresponding fixed point algebra , we present a sys…
Noncommutative Coverings of Quantum Tori
Kay Schwieger, Stefan Wagner
We introduce a framework for coverings of noncommutative spaces. Moreover, we study noncommutative coverings of irrational quantum tori and characterize all such coverings that are…
Secondary Characteristic Classes of Lie Algebra Extensions
Stefan Wagner
We introduce a notion of secondary characteristic classes of Lie algebra extensions. As a spin-off of our construction we obtain a new proof of Lecomte's generalization of the Cher…
Part III, Free Actions of Compact Quantum Groups on C*-Algebras
Kay Schwieger, Stefan Wagner
We study and classify free actions of compact quantum groups on unital C*-algebras in terms of generalized factor systems. Moreover, we use these factor systems to show that all fi…
Third Group Cohomology and Gerbes over Lie Groups
Jouko Mickelsson, Stefan Wagner
The topological classification of gerbes, as principal bundles with the structure group the projective unitary group of a complex Hilbert space, over a topological space is giv…
Part II, Free Actions of Compact Groups on C*-Algebras
Kay Schwieger, Stefan Wagner
We study a simple subclass of free actions of non-Abelian groups on unital C*-algebras, namely cleft actions. These are characterized by the fact that the associated noncommutative…
Part I, Free Actions of Compact Abelian Groups on C*-Algebras
Kay Schwieger, Stefan Wagner
We study free and compact group actions on unital C*-algebras. In particular, we provide a complete classification theory of these actions for compact Abelian groups and explain it…
On Noncommutative Principal Bundles with Finite Abelian Structure Group
Stefan Wagner
Let be a finite abelian group. A dynamical system with transformation group is a triple , consisting of a unital locally convex algebra , the finite abelian gro…
Free Group Actions from the Viewpoint of Dynamical Systems
Stefan Wagner
In this paper we present a new characterization of free group actions (in classical differential geometry), involving dynamical systems and representations of the corresponding tra…
Extending Characters of Fixed Point Algebras
Stefan Wagner
A dynamical system is a triple , consisting of a unital locally convex algebra , a topological group and a group homomorphism $α:G\rightarrow\Aut(A)$, which induces…
A Geometric Approach to Noncommutative Principal Torus Bundles
Stefan Wagner
A (smooth) dynamical system with transformation group is a triple , consisting of a unital locally convex algebra , the -torus $\mathbb{T}^…
A Geometric Approach to Noncommutative Principal Bundles
Stefan Wagner
From a geometrical point of view it is, so far, not sufficiently well understood what should be a "noncommutative principal bundle". Still, there is a well-developed abstract algeb…