On Spectrum of Product of Two Operators
Xiong Chang · Shinjang dashösi ilmiy jurnili · 2003
Let A and B be two linear bounded operators on a Hilbert space H.In this notes we give a necessary and sufficient condition of \$σ(AB)=σ(BA).\$Given B,we also get a necessary and sufficient condition so that \$σ(AB)=σ(BA)\$ for any A.