Brzeziński, T.
(Symmetry, Integrability and Geometry: Methods and Applications, 2014)
Recent results by Krähmer [Israel J. Math. 189 (2012), 237-266] on smoothness of Hopf-Galois extensions and by Liu [arXiv:1304.7117] on smoothness of generalized Weyl algebras are used to prove that the coordinate algebras ...