Matrix:
\begin{bmatrix}0&1&1&0\\0&0&1&0\\…&…&…&..\\…&…&…&..\end{bmatrix}
\(\begin{bmatrix}0&1&1&0\\0&0&1&0\\…&…&…&..\\…&…&…&..\end{bmatrix}\)

\underbrace{}
\widetilde{}
\array or \begin{aligned}


& is used for aligned
my code is:

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