On Weyl’s theorem and its converse
On Weyl’s theorem and its converse
In this paper we study Weyl’s theorem and von Neumann’s converse of Weyl’s theorem for the classes of all operators of the form <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper T Subscript f Superscript negative 1 Baseline upper T Subscript g"> <mml:semantics> <mml:mrow> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mi>f</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>−<!-- − --></mml:mo> <mml:mn>1</mml:mn> …