Abstract:
We obtain new gauge-invariant forms of two-dimensional integrable systems of nonlinear equations: the Sawada–Kotera and Kaup–Kuperschmidt system, the generalized system of dispersive long waves, and the Nizhnik–Veselov–Novikov system. We show how these forms imply both new and well-known two-dimensional integrable nonlinear equations: the Sawada–Kotera equation, Kaup–Kuperschmidt equation, dispersive long-wave system, Nizhnik–Veselov–Novikov equation, and modified Nizhnik–Veselov–Novikov equation. We consider Miura-type transformations between nonlinear equations in different gauges.