Browsing Teses e dissertações by Subject "Hipoeliticidade global"
Now showing items 1-1 of 1
(Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Matemática - PPGM, , 11/08/2003)A necessary and sufficient condition is given for a sum of squares operator to be globally hypoelliptic. This condition is expressed in terms of Diophatine approximation properties of the coefficients. The proof of the ...