2 papers
math.SP2016
Numerical range with respect to a family of projections
W. Dada, N. Erkurşun, J. Kerner
In this note we introduce the concept of the numerical range of a bounded linear operator with respect to a family of projections. We give a precise definition and elaborate on its…
math.FA2015
A semigroup approach to the numerical range of operators on Banach spaces
Martin Adler, Waed Dada, Agnes Radl
We introduce the numerical spectrum of an (unbounded) linear operator on a Banach space and study its properties. Our definition is closely relat…