Approximating pseudopotentials for evolution equations containing a small parameter

For nonlinear partial differential equations that cannot be integrated by the inverse scattering method, an approach that makes it possible to construct Wahlquist—Estabrook approximating pseudopotentials is proposed. The method is used to find an approximate Lax pair and conservation laws of the Kawahara equation.Moscow Engineering Physics Institute. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 91, No. 3, pp. 355–362, June, 1992.