17 citations · 56 across the 19 of their papers we have counts for
21 papers
Twisted Dirac operator on quantum SU(2) in disc coordinates
Ulrich Kraehmer, Elmar Wagner
The quantum disc is used to define a noncommutative analogue of a dense coordinate chart and of left-invariant vector fields on quantum SU(2). This yields two twisted Dirac operato…
A universal enveloping algebra for cocommutative rack bialgebras
Ulrich Kraehmer, Friedrich Wagemann
We construct a bialgebra object in the category of linear maps LM from a cocommutative rack bialgebra. The construction does extend to some non-cocommutative rack bialgebras, as is…
A Hopf algebra without modular pair in involution
Sebastian Halbig, Ulrich Kraehmer
The aim of this short note is to communicate an example of a finite-dimensional Hopf algebra that does not admit a modular pair in involution in the sense of Connes and Moscovici.
The nodal cubic and quantum groups at roots of unity
Ulrich Kraehmer, Manuel Martins
In a recent article, the coordinate ring of the nodal cubic was given the structure of a quantum homogeneous space. Here the corresponding coalgebra Galois extension is expressed i…
(Weak) incidence bialgebras of monoidal categories
Ulrich Kraehmer, Lucia Rotheray
Incidence coalgebras of categories in the sense of Joni and Rota are studied, specifically cases where a monoidal product on the category turns these into (weak) bialgebras. The ov…
Cyclic vs mixed homology
Ulrich Kraehmer, Dylan Madden
The spectral theory of the Karoubi operator due to Cuntz and Quillen is extended to general mixed (duchain) complexes, that is, chain complexes which are simultaneously cochain com…