Suppose we have a matrix $M\in\Bbb Q^{n\times n}$ with no $0$ elements and we write as sum of two matrices $M_1$ and $M_2$ on following constraint.
$M_{1,ij}=M_{ij}$ and $M_{2,ij}=0$ or $M_{1,ij}=0$ and $M_{2,ij}=M_{ij}$ or $M_{1,ij}=M_{2,ij}=\frac{M_{ij}}2$.
If $M$ is of rank $1$ under what conditions can we expect ranks of $M_1$ and $M_2$ to be bound by $O(1)$ or $O(\log\|M\|_2)$?
If $M$ is of rank $1$ under what conditions on the split can we expect ranks of $M_1$ and $M_2$ to be bound by $O(\log\|M\|_2)$?