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Given a matrix $n \times m$, I want to find the submatrices $a \times m$ by selecting $a$ columns such that their rank is minimal. Can this problem be solved efficiently?

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    $\begingroup$ Selecting one arbitrary column gives you rank 1. $\endgroup$ Commented Nov 7 at 0:09
  • $\begingroup$ Do you want to find one submatrix of all submatrices $a \times m$ with smallest rank? Is $a$ fixed too? $\endgroup$ Commented Nov 7 at 8:12
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    $\begingroup$ What's the size of $a$ compared to $n$? I haven't thought of this much, but it has an LWE/code decoding feel, so I'm not very hopeful $\endgroup$ Commented Nov 7 at 9:30
  • $\begingroup$ In a previous comment, now deleted, I said that the number of columns is fixed. I meant the number of row, that is $a$. $\endgroup$
    – Alm
    Commented Nov 7 at 9:36
  • $\begingroup$ Let me say that a is between square root of n and n/2. $\endgroup$
    – Alm
    Commented Nov 7 at 9:40

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