Minimal Factorizations of Rational Matrix Functions

Let W be a rational n×n matrix function, and let λ0∈θ. In a deleted neighbourhood of λ0 we have the following expansion $$ [tex]W(\lambda ) = {\sum\limits_{j=-q}^\infty {(\lambda - {\lambda _0})} ^j}{W_j}[/tex]$$ (4.1) .