On the Gieseker Harder-Narasimhan filtration for principal bundles

Abstract

We give an example of an orthogonal bundle where the Harder-Narasimhan filtration, with respect to Gieseker semistability, of its underlying vector bundle does not correspond to any parabolic reduction of the orthogonal bundle. A similar example is given for the symplectic case.

Final version

References in corpus (4)

• Moduli Spaces for Principal Bundles in Arbitrary Characteristic
• Stable tensors and moduli space of orthogonal sheaves
• A closer look at semistability for singular principal bundles
• Harder-Narasimhan filtration for rank 2 tensors and stable coverings