 Vakhitov–Kolokolov stability criterion

The Vakhitov–Kolokolov stability criterion is a condition used in the study of nonlinear wave phenomena, particularly in the stability analysis of solitary waves or pulses in various physical systems, such as nonlinear optics and fluid dynamics. The criterion helps determine whether a given solitary wave solution to a nonlinear partial differential equation is stable or unstable under small perturbations.