Semi-scalar equivalence of polynomial matrices
Polynomial $n\times n$ matrices $A(λ)$ and $B(λ)$ over a field $\mathbb F $ are called semi-scalar equivalent if there exist a nonsingular $n\times n$ matrix $P$ over the field $\mathbb F $ and an invertible $n\times n$ matrix $Q(λ)$ over the ring ${\mathbb F}[λ]$ such that $A(λ)=P B(λ)Q(λ).$ The semi-scalar equivalence of matrices over a field $ {\mathbb F} $ contain the problem of similarity between two families of matrices. Therefore, these equivalences of matrices can be considered a difficult problem in linear algebra. The aim of the present paper is to present the necessary and sufficient conditions of semi-scalar equivalence of nonsingular matrices $A(λ)$ and $ B(λ) $ over a field ${\mathbb F }$ of characteristic zero in terms of solutions of a homogenous system of linear equations. We also establish similarity of monic polynomial matrices $A(λ)$ and $B(λ)$ over a field.