We present some recent results, obtained jointly with Detlef Müller, on solvability of operators of the form where the are left-invariant vector fields on the Heisenberg group, such that () are the only nontrivial relations, and is a complex symmetric matrix with semi-definite real part. The presentation also contains references on the work done in the past few years in this area.
@article{JEDP_2000____A15_0, author = {Ricci, Fulvio}, title = {Solvability of second-order left-invariant differential operators on the Heisenberg group}, journal = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, year = {2000}, pages = {1-10}, mrnumber = {2002c:22018}, zbl = {01808705}, language = {en}, url = {http://dml.mathdoc.fr/item/JEDP_2000____A15_0} }
Ricci, Fulvio. Solvability of second-order left-invariant differential operators on the Heisenberg group. Journées équations aux dérivées partielles, (2000), pp. 1-10. http://gdmltest.u-ga.fr/item/JEDP_2000____A15_0/
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