grandes-ecoles 2016 QIII.A

grandes-ecoles · France · centrale-maths1__mp 3x3 Matrices Matrix Algebraic Properties and Abstract Reasoning
Let $A$ be a primitive matrix in $\mathcal{M}_n(\mathbb{R})$.
Show that for all $i \neq j$ there exists in $A$ an elementary path from $i$ to $j$ of length $\ell \leqslant n-1$, and that for all $i$ there exists in $A$ an elementary circuit passing through $i$ of length $\ell \leqslant n$.
Let $A$ be a primitive matrix in $\mathcal{M}_n(\mathbb{R})$.

Show that for all $i \neq j$ there exists in $A$ an elementary path from $i$ to $j$ of length $\ell \leqslant n-1$, and that for all $i$ there exists in $A$ an elementary circuit passing through $i$ of length $\ell \leqslant n$.