Let $B \geq A \geq 0$ and $M \geq 0$ be real symmetric matrices. Is it true that
$B M B \geq A M A$, i.e., $B M B - A M A \geq 0$?
Let $B \geq A \geq 0$ and $M \geq 0$ be real symmetric matrices. Is it true that
$B M B \geq A M A$, i.e., $B M B - A M A \geq 0$?