An extension of the modified Sawada–Kotera equation and conservation laws
He Guo-Liang(何国亮)a)b)† and Geng Xian-Guo(耿献国)a)
a Department of Mathematics, Zhengzhou University, Zhengzhou 450001, China;
b Department of Mathematics and Information Science, Zhengzhou University of Light Industry, Zhengzhou 450002, China
Abstract Based on the modified Sawada--Kotera equation, we introduce a 3?3 matrix spectral problem with two potentials and derive a hierarchy of new nonlinear evolution equations. The second member in the hierarchy is a generalization of the modified Sawada--Kotera equation, by which a Lax pair of the modified Sawada--Kotera equation is obtained. With the help of the Miura transformation, explicit solutions of the Sawada--Kotera equation, the Kaup--Kupershmidt equation, and the modified Sawada--Kotera equation are given. Moreover, infinite sequences of conserved quantities of the first two nonlinear evolution equations in the hierarchy and the modified Sawada--Kotera equation are constructed with the aid of their Lax pairs.
Fund: Project supported by the National Natural Science Foundation of China (Grant No. 11171312) and the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 200804590008).
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