Let $A\in\mathbb{R}^{m\times m} $ and $B\in\mathbb{R}^{m\times m}$. It is known that $rank(A+B)\leq rank(A)+rank(B)$. My question is when does equality holds for this inequality? What is the condition for the case of more than 2 matrices?
2026-03-30 14:57:11.1774882631
Rank of a matrix sum: equality case
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