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Ludwig
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Condition for non-vanishing trace

Let $A$ and $B$ be two full column-rank real matrices of dimension $n\times m$, $n\ge m$. Let $P$ be an $m\times m$ positive definite matrix.

Question. Does there always exist a symmetric $m\times m$ matrix $X$ such that $$ \mathrm{tr}(P(A^\top XB+B^\top X A))\ne 0\ \ ? $$

Ludwig
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