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SUMMARY:On maximally hypoelliptic differential operators.
DTSTART:20260113T130000Z
DTEND:20260113T140000Z
DTSTAMP:20260424T103000Z
UID:indico-event-14801@indico.math.cnrs.fr
DESCRIPTION:Speakers: Omar Mohsen (Paris-Saclay)\n\n\n\n\n\n\n\n\nThe clas
 s of maximally hypoelliptic differential operators is a large class of dif
 ferential operators which contains elliptic operators as well as Hörmand
 er’s sum of squares. I will present our work where we define a principa
 l symbol generalising the classical principal symbol for elliptic operato
 rs which should be thought of as the analogue of the principal\nsymbol in 
 sub-Riemannian geometry. Our main theorem is that maximal hypoellipticity
  is equivalent to invertibility of our principal symbol\, thus generalisi
 ng the main regularity theorem for elliptic operators and confirming a co
 njecture of Helffer and Nourrigat.  Our proof differs from the proof of t
 he elliptic regularity theorem in its essential use of C* algebras. I wil
 l try in the end to explain the role of C* algebras in this theory.\n\n\n\
 n\n\n\n \n\n \n\n \n\n\nhttps://indico.math.cnrs.fr/event/14801/
LOCATION:Fokko (ICJ)
URL:https://indico.math.cnrs.fr/event/14801/
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