The essential spectrum of some Toeplitz operators
The essential spectrum of some Toeplitz operators
The localization techniques of Douglas and Sarason are used to obtain the essential spectrum of the Toeplitz operator <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper T Subscript phi"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>T</mml:mi> <mml:mi>φ<!-- φ --></mml:mi> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{T_\varphi }</mml:annotation> </mml:semantics> </mml:math> </inline-formula> for which <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="phi"> <mml:semantics> …