2 problems

Bourin's symmetric-norm extension of Corollary 1.2. The same inequality should hold with the operator norm replaced by every symmetric norm. In particular, the trace inequality (2)…

Let $A$ and $B$ be normal matrices of the same size, let $Z$ be an expansive matrix, meaning $Z^*Z\ge I$, let $f:[0,\infty)\to[0,\infty)$ be non-negative and concave, and let…