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Global Hypoellipticity of a Class of Second Order Operators

Published online by Cambridge University Press:  20 November 2018

Adalberto P. Bergamasco
Affiliation:
Departamento de Matemática, Universidade Federal de São Carlos, Caixa Postal 676-13.565-905, São Carlos, SP Brazil e-mail:, apbergam@icmsc.usp.ansp.br
Sérgio Luís Zani
Affiliation:
Instituto de Ciências Matemdticas de São Carlos, Universidade de São Paulo, Caixa Postal 668-13.560-970, São Carlos, SP Brazil
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Abstract

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We show that almost all perturbations P — λ, λ € C, of an arbitrary constant coefficient partial differential operator P are globally hypoelliptic on the torus. We also give a characterization of the values λ € C for which the operator is globally hypoelliptic; in particular, we show that the addition of a term of order zero may destroy the property of global hypoellipticity of operators of principal type, contrary to that happens with the usual (local) hypoellipticity.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1994

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