On the binary relation ${\le }_u$ on self-adjoint Hilbert space operators

M. S. Moslehian, S. M. S. Nabavi Sales, H. Najafi

Given self-adjoint operators $A,B\in \mathbb{B}(\mathcal{H})$ it is said $A{\le }_{u}B$ whenever $A\le U^{\ast }BU$ for some unitary operator $U$. We show that $A{\le }_{u}B$ if and only if $f…