Sagun Chanillo, Bernard Helffer, Ari Laptev
Published 2002-11-20, updated 2002-12-07Version 3
Motivated by the problems of analytic hypoellipticity, we show that a special family of compact non self-adjoint operators has a non-zero eigenvalue. We recover old results by Christ,Hanges, Himonas, Pham-The-Lai and Robert proved by using ordinary differential equations. We show our method applies to higher dimensional cases, giving in particular a new class of hypoelliptic but not analytic hypoelliptic operators.
Comments: 22 pages, theorem 4.3 in new version is improved from m>18(old) to m>5(new) Proofs simplified considerably and typos fixed
Journal: J. Functional Analysis, 209(2), 2004, 425-443
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