说明：  This chapter is devoted to the study of the stability for singular systems in both the continuous and discrete contexts. The definitions of regularity and non-impulsiveness (in the continuous case) or causality (in the discrete case) have played important roles in the analysis of singular systems. Specifically, regularity guarantees the existence and uniqueness of a solution to a given singular system, while non-impulsiveness ensures no infinite dynamical modes in a singular system.