In a note recently published
W. Leighton presents the following theorem.
Theorem 1. Let f(x) = (x1,⋯,xn) be of class C2 in En. Suppose that f(x) has an
isolated relative minimum at x = 0, and that f(0) = 0. If there is a point x = 0 where
f(x) = 0, then f(x) must have at least one critical point, finite or infinite, in addition
to that at the origin.
The proof employed by Prof. Leighton of Theorem (1) is based upon the
theory of Morse and for this the condition that f(x) belongs to class C2 is
essential.
In what follows we shall give a proof of Theorem (1) for functions of class
C1.
|