Lemma 2.3 . [04TS]

Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.

Complete original source context · Original author HTML

Lemma 2.3.

Assume

\det D^{2}u\geq 1

in $B_{1}\subset\mathbb{R}^{n}$ . Then $u$ cannot vanish on a subspace of dimension $\frac{n}{2}$ or higher.