Let T be a bounded linear operator acting on a separable infinite dimension
al Hilbert space. Let epsilon be a positive number. In this article, we pro
ve that the perturbation of T by a compact operator K with parallel to K pa
rallel to < epsilon can be strongly irreducible if T is a quasitriangular o
perator with the spectrum sigma(T) connected. The Main Theorem of this arti
cle nearly answers the question below posed by D. A. Herrero.
Suppose that T is a bounded linear operator acting on a separable infinite
dimensional Hilbert space with sigma(T) connected. Let epsilon > 0 be given
. Is there a compact operator K with parallel to K parallel to < epsilon su
ch that T + K is strongly irreducible?