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An elementary proof of Fedi\uı's theorem and extensions

David S. Tartakoff
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Abstract

We present an elementary, $L^2,$ proof of Fedi\uı's theorem on arbitrary (e.g., infinite order) degeneracy and extensions. In particular, the proof allows and shows $C^\infty,$ Gevrey, and real analytic hypoellipticity, and allows the coefficents to depend on the remaining variable as well.

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David S. Tartakoff. 2006-09-28. An elementary proof of Fedi\uı's theorem and extensions. https://arxiv.org/abs/math/0609778

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