A selfadjoint operator A selfadjoint operator T ¹ 0 on a Hilbert space such that T is neither positive nor negative.

******************************

Consider T = (
-1
0
0
1
) belonging to B(C2), x = (
1
0
) and h = (
0
1
). Then < Tx, x > = -1 and < Th, h > = 1. Hence the selfadjoint operator T is neither positive nor negative.


File translated from TEX by TTH, version 2.70.
On 22 Feb 2001, 00:21.