Nonstandard operators in Grassmannian geometry
  We present a construction of curved analogues of the nonstandard operators on Grassmannians parallel to the construction of the Paneitz operator via the curved Casimir operator, but technically more demanding. In particular, the construction breaks down in the presence of torsion. In the second part, we prove that the nonstandard operators are not strongly invariant. 
Ale\v{s} N\'avrat
math.DG