Kazaryan, G. G. On a functional index of hypoellipticity. (English. Russian original) Zbl 0609.35027 Math. USSR, Sb. 56, 333-347 (1987); translation from Mat. Sb., Nov. Ser. 128(170), No. 3, 339-353 (1985). For a special family of hypoelliptic operators containing the semielliptic operators the functional characteristic of hypoellipticity is introduced, which is equivalent to hypoellipticity index in the elliptic case and sharpens it in the general case. Reviewer: D.Fage MSC: 35H10 Hypoelliptic equations 35E20 General theory of PDEs and systems of PDEs with constant coefficients Keywords:functional index; constant coefficients; Gevrey classes; regular hypoelliptic equation; hypoelliptic operators; semielliptic operators; functional characteristic PDFBibTeX XMLCite \textit{G. G. Kazaryan}, Math. USSR, Sb. 56, 333--347 (1987; Zbl 0609.35027); translation from Mat. Sb., Nov. Ser. 128(170), No. 3, 339--353 (1985) Full Text: DOI