The homogeneous balance method, Lax pair, Hirota transformation and a general fifth-order KdV equation

By considering the inhomogeneities of media, a generalized variable-coefficient Kadomtsev-Petviashvili (vc-KP) equation is investigated, which can be used to describe many nonlinear phenomena in fluid dynamics and plasma physics. In this paper, we systematically investigate complete integrability of the generalized vc-KP equation under a integrable constraint condition. With the aid of a generalized Bells polynomials, its bilinear formulism, bilinear B\"{a}cklund transformati...

The nonlocal symmetry is derived from the known Darboux transformation (DT) of the Hirota-Satsuma coupled KdV (HS-cKdV) system, and infinitely many nonlocal symmetries are obtained by introducing some internal parameters. By extending the HS-cKdV system to an auxiliary system with five dependent variables, the prolongation is found to localize the nonlocal symmetry related to the DT. Base on the enlarged system, the finite symmetry transformations and similarity reductions ab...

Bilinearization of a given nonlinear partial differential equation is very important not only to find soliton solutions but also to obtain other solutions such as the complexitons, positons, negatons, and lump solutions. In this work we study the bilinearization of nonlinear partial differential equations in $(2+1)$-dimensions. We write the most general sixth order Hirota bilinear form in $(2+1)$-dimensions and give the associated nonlinear partial differential equations for ...

The constraints for evolution equations with some special form of Lax pair are first investigated. We show by examples how the method is rooted in the classical literatures and how the ignored constraints provide nontrivial solutions. Then we showed, by the example of the KdV, how this special form of Lax pair may be found by the method of EW. At last we propose how constraints should be imposed for general Lax pairs including nonlinear ones, with which the true Lax pairs and...

We carry out group analysis of a class of generalized fifth-order Korteweg-de Vries equations with time dependent coefficients. Admissible transformations, Lie symmetries and similarity reductions of equations from the class are classified exhaustively. A criterion of reducibility of variable coefficient fifth-order KdV equations to their constant coefficient counterparts is derived. Some exact solutions are presented.

Shallow water waves phenomena in nature attract the attention of scholars and play an important role in fields such as tsunamis, tidal waves, solitary waves, and hydraulic engineering. Hereby, fortheshallowwaterwavesphenomenainvariousnaturalenvironments, westudytheKdV-Calogero-Bogoyavlenskii-Schiff (KdV-CBS) equation. Based on the binary Bell polynomial theory, a new general bilinear B\"acklund transformation, Lax pair and infinite conservation laws of the KdV-CBS equation ar...

We study to unify soliton systems, KdV/mKdV/sinh-Gordon, through SO(2,1) $\cong$ GL(2,$\mathbb R$) $\cong$ M\"{o}bius group point of view, which might be a keystone to exactly solve some special non-linear differential equations. If we construct the $N$-soliton solutions through the KdV type B\"{a}cklund transformation, we can transform different KdV/mKdV/sinh-Gordon equations and the B\"{a}cklund transformations of the standard form into the same common Hirota form and the s...

In the paper we discuss the B\"acklund transformation of the KdV equation between solitons and solitons, between negatons and negatons, between positons and positons, between rational solution and rational solution, and between complexitons and complexitons. We investigate the conditions that Wronskian entries satisfy for the bilinear B\"acklund transformation of the KdV equation. By choosing suitable Wronskian entries and the parameter in the bilinear B\"acklund transformati...

Hirota's bilinear approach is a very effective method to construct solutions for soliton systems. In terms of this method, the nonlinear equations can be transformed into linear equations, and can be solved by using perturbation method. In this paper, we study the bilinear Boussinesq equation and obtain its bilinear B\"{a}cklund transformation. Starting from this bilinear B\"{a}cklund transformation, we also derive its Lax pair and test its integrability.

A general form of the fifth-order nonlinear evolution equation is considered. Helmholtz solution of the inverse variational problem is used to derive conditions under which this equation admits an analytic representation. A Lennard type recursion operator is then employed to construct a hierarchy of Lagrangian equations. It is explicitly demonstrated that the constructed system of equations has a Lax representation and two compatible Hamiltonian structures. The homogeneous ba...