Note also that when E → ±∞, equation (1.1) transforms into another renowned (2 + 1)dimensional analog of KdV, Kadomtsev-Petviashvili equation (KP-I and KP-II, respectively). In addition, a dispersionless analog of (1.1) at E = 0 was derived in [KM] in the framework of a geometrical optics model. Equation (1.1) is contained implicitly in [M] as an equation… (More)