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Hugo Chapdelaine
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General criterion to find a Z-basis in a fixed generating subset

Let $V=\mathbf{Z}^N$ be a free $\mathbf{Z}$-module of rank $N$. Let $S\subseteq V$ be a fixed finite subset.

Consider the submodule $M:=\langle S\rangle\leq V$ generated by $S$. We know form the general theory that $M$ is a free $\mathbf{Z}$-module of rank $\leq N$.

Q: Is there a theoritical criterion to determine when it is possible to find a subset $B\subseteq S$ such that $B$ is a $\mathbf{Z}$-basis of $M$?

If $\#S=r$, then taking the standard basis of $V$, one may associate to $S$ an $r\times n$ matrix. So a possible criterion (here I'm specalutating) could consist (partly) at looking at the gcd of determinants of sufficiently many minors of suitable sizes.

Hugo Chapdelaine
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