Invariant zeros in singular systems - Algebraic criterions of nondegeneracy

The question of how the classical concept of the Smith zeros of a LTI continuous-time singular control system S(E,A,B,C,D) can be generalized and related to state-space methods is discussed. The zeros are defined as those complex numbers for which there exists a zero direction with nonzero state-zero direction. Such a definition admits an infinite number of zeros (then the system is called degenerate). Algebraic criterions of degeneracy/nondegeneracy based on Weierstrass-Kronecker canonical form of the system and on the first nonzero Markov parameter are analyzed.