Abstract. Let A,B be positive semidefinite matrices and
$|||\cdot|||$ any unitarily invariant norm on the space of matrices. We show
$ |||f(A) + f(B)||| \geq |||f(A + B)|||$ for any non-negative… Expand

Let p, q > 0 satisfy 1/p + 1/q = 1. We prove that for any pair A, B of n × n complex matrices there is a unitary matrix U, depending on A, B, such that
$$U*\left| {AB*} \right|U \leqslant {\left|… Expand