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Hypoelliptic second order differential equations. (English) Zbl 0156.10701

##### Keywords:
partial differential equations
##### References:
 [1] Hochschild, G.,The structure of Lie groups. Holden–Day Inc., San Francisco, London, Amsterdam, 1965. [2] Hörmander, L., Pseudo-differential operators and hypoelliptic equations. To appear inAmer. Math. Soc. Proc. Symp. Pure Math., 10 (1967). [3] ,Linear partial differential operators. Springer-Verlag, Berlin-Göttingen-Heidelberg, 1963. [4] Il’in, A. M., On a class of ultraparabolic equations. (Russian.)Doklady Akad. Nauk SSSR, 159 (1964), 1214–1217. Also inSoviet Math. Dokl., 5 (1964), 1673–1676. [5] Kohn, J. J., Boundaries of complex manifolds.Proc. Conf. Complex Analysis (Minneapolis 1964) 81–94. Springer Verlag, Berlin, 1965. [6] Kohn, J. J. &Nirenberg, L., Non coercive boundary value problems.Comm. Pure Appl. Math. 18 (1965), 443–492. · Zbl 0125.33302 · doi:10.1002/cpa.3160180305 [7] Kohn, J. J. & Nirenberg, L., Degenerate elliptic-parabolic equations of second order. To appear inComm. Pure Appl. Math. [8] Kolmogorov, A. N., Zufällige Bewegungen,Ann. of Math. (2), 35 (1934), 116–117. · doi:10.2307/1968123 [9] Nirenberg, L. &Trèves, F., Solvability of a first order linear partial differential equation.Comm. Pure Appl. Math., 16 (1963), 331–351. · Zbl 0117.06104 · doi:10.1002/cpa.3160160308 [10] Olejnik, O. A., Linear second order equations with non-negative characteristic form. (Russian.)Mat. Sb., 69 (1966), 111–140. [11] Weber, M., The fundamental solution of a degenerate partial differential equation of parabolic type.Trans. Amer. Math. Soc., 71 (1951), 24–37. · doi:10.1090/S0002-9947-1951-0042035-0