Essential Numerical Range in β(P1)
Proceedings of the American Mathematical Society
In recent years, the numerical range lifting problem has been solved for operators on , , and on certain Orlicz spaces . Specifically, given an operator , there exists a compact perturbation such that the numerical range of equals the essential numerical range of . This result has also been established for essentially Hermitian operators on . In the present paper, the authors establish this result for all operators on .
David A. Legg and Douglas W. Townsend (1981).
Essential Numerical Range in β(P1). Proceedings of the American Mathematical Society.81 (4), 541-545.