Gevrey hypoellipticity for partial differential equations with characteristics of higher multiplicity.
We propose a unified approach, based on methods from microlocal analysis, for characterizing the hypoellipticity and the local solvability in and Gevrey classes of semilinear anisotropic partial differential operators with Gevrey nonlinear perturbations, in dimension . The conditions for our results are imposed on the sign of the lower order terms of the linear part of the operator, see Theorem 1.1 and Theorem 1.3 below.
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