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On global hypoellipticity of vector fields Jorge Hounie (1982) Journées équations aux dérivées partielles
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On hypoellipticity in g M. Nedeljkov, S. Pilipović (2002) Bulletin, Classe des Sciences Mathématiques et Naturelles, Sciences mathématiques
On local and global analytic and Gevrey hypoellipticity Michael Christ (1995) Journées équations aux dérivées partielles
On local properties of some classes of infinitely degenerate elliptic differential operators. Tri, N.M. (2001) Rendiconti del Seminario Matematico
On the Eigenvalue of a Class of Hypoelliptic Operators. A. Menikoff, J. Sjöstrand (1978) Mathematische Annalen
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On the Functional Dimension of Solution Spaces of Hypoelliptic Partial Differential Operators. Michael Langenbruch (1985) Mathematische Annalen
On the Gevrey analyticity of solutions of semilinear perturbations of powers of the Mizohata operator. Tri, N.M. (1999) Rendiconti del Seminario Matematico
On the Gevrey hypo-ellipticity of sums of squares of vector fields Antonio Bove, François Treves (2004) Annales de l’institut Fourier The article studies a second-order linear differential operator of the type - L = X 1 2 + ...
One dimensional symmetry in the Heisenberg group Isabeau Birindelli, Jyotshana Prajapat (2001) Annali della Scuola Normale Superiore di Pisa - Classe di Scienze
Opérateurs différentiels hypoelliptiques et groupes nilpotents B. Helffer, J. Nourrigat (1978/1979) Séminaire Équations aux dérivées partielles (Polytechnique)
Opérateurs hypoelliptiques sur des groupes nilpotents B. Helffer, F. Nourrigat (1977/1978) Séminaire Équations aux dérivées partielles (Polytechnique)
Operatori differenziali a coefficienti costanti di tipo iperbolico-(ipo)ellittico Giuseppe Zampieri (1984) Rendiconti del Seminario Matematico della Università di Padova