Inverse M matrices sufficient condition for reversing inequality

linear algebramatrices

I am asking out of curiosity, from a related question: Element-wise ordering of the inverse of two M-matrices.
I know that in general the converse is not true.
But suppose that we are given an inverse M matrix $A$ and identity matrix $I$ with $A \leq I$ (entrywise ordering), when can we say $A^{-1}\geq I$ holds true?
Try: Because $A$ is an inverse M matrix, I tried by assuming, suppose $A^{-1}$ is strictly diagonally dominant, then manipulate to show that the inequality will reverse, but so far no luck. Any hint or idea to try pursue will be really helpful.

Best Answer

If $A\le I$, $A$ is a diagonal matrix. Since $A$ is the inverse of an $M$-matrix, it is a positive diagonal matrix. The assumption $A\le I$ thus implies that all diagonal entries of $A$ lie inside $(0,1]$. Hence $A^{-1}\ge I$.

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