Electron.n. J. Diff. Eqns. Vol. 1993(1993), No. 3, pp. 1-9.
Lawrence C. Evans
I present some elementary maximum principle arguments, establishing interior gradient bounds and Harnack inequalities for both $u$ and |Du|, where u is a smooth solution of the degenerate elliptic PDE
Delta_infinity u = 0 .
These calculations in particular extend to higher dimensions G. Aronsson's assertion that a nonconstant, smooth solution can have no interior critical point.
An addendum was placed on March 9, 1994. See last page of this article.
Submitted July 20, 1993. Published October 12, 1993.
Math Subject Classification: 35J70, 26A16.
Key Words: Lipschitz extensions, Harnack inequalities.
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