The invariant differential operators on a manifold with a given parabolic structure come in two classes, standard and non-standard, and can be further subdivided into regular and singular ones. The standard regular operators come in repeated patterns, the Bernstein-Gelfand-Gelfand sequences, described by Hasse diagrams. In this paper, the authors present an alternative characterization of Hasse diagrams, which is quite efficient in the case of low gradings. Several examples are given.
@article{701712,
title = {Hasse diagrams for parabolic geometries},
booktitle = {Proceedings of the 22nd Winter School "Geometry and Physics"},
series = {GDML\_Books},
publisher = {Circolo Matematico di Palermo},
address = {Palermo},
year = {2003},
pages = {[133]-141},
mrnumber = {MR1982440},
zbl = {1047.53014},
url = {http://dml.mathdoc.fr/item/701712}
}
Krump, Lukáš; Souček, Vladimír. Hasse diagrams for parabolic geometries, dans Proceedings of the 22nd Winter School "Geometry and Physics", GDML_Books, (2003), pp. [133]-141. http://gdmltest.u-ga.fr/item/701712/