# I-AB 和 I-BA 不得不说的故事
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**Theorem** Let \\( A, B \in M_n(\mathbb{C}) \\).
$$
I_n-AB \text{ is invertible} \Longleftrightarrow I_n-BA \text{ is invertible},
$$
where \\( I_n \in M_n(\mathbb{C}) \\) is identity matrix.
[PDF](015/main.pdf)
[TEX](015/main.tex)