@article {28126,
	title = {A pseudodifferential calculus for maximally hypoelliptic operators and the Helffer-Nourigat conjecture},
	year = {Submitted},
	abstract = {<span>Given a filtration of the module of vector fields on a smooth manifold, we define a pseudodifferential calculus where the order of a vector field is given by the filtration. We show that pseudodifferential operators have a well-defined principal symbol for a subset of the unitary representations of the osculating groups. We prove a Rockland-type theorem, showing that the invertibility of the principal symbol is equivalent to maximal hypoellipticity. This answers affirmatively a conjecture due to Helffer and Nourrigat.</span>},
	url = {https://arxiv.org/abs/2201.12060},
	author = {Iakovos Androulidakis and Omar Mohsen and Robert Yuncken}
}
