Sturm-Picone comparison theorems for nonlinear impulsive differential equations with discontinuous solutions.

The nonlinear versions of Sturm-Picone comparison theorem as well as Leighton's variational lemma and Leighton's theorem for regular and singular nonlinear impulsive differential equations with discontinuous solutions having fixed moments of impulse actions are established. Although discontinuity of the solutions causes some difficulties, these new comparison theorems cover the old ones where impulse effects are dropped. [ABSTRACT FROM AUTHOR]