Hypoelliptic operators of principal type with infinite degeneracy
Hypoelliptic operators of principal type with infinite degeneracy
Let us recall that {\) is necessary for adjoint operator P* of P to be locally solvable (see Hormander [6; Theorem 26.4.7], cf. Moyer [14]). Since it follows from the hypoellipticity of P that P* is locally solvable, it is reasonable to assume the condition (\). By supplying the missing …