Four (2 + 1)-dimensional integrable extensions of the KdV equation: Multiple-soliton and multiple singular soliton solutions

In this work, four (2 + 1)-dimensional nonlinear completely integrable equations, generated by extending the KdV equation are developed. The necessary condition for the complete integrability of these equation are formally derived. Multiple-soliton solutions and multiple singular soliton solutions are determined to emphasize the compatability of these models. The dispersion relations of these models are characterized by distinct physical structures. The resonance phenomenon for these equations does not exist for any model.