The generalized Wronskian solutions of a inverse KdV hierarchy

A hierarchy of the inverse KdV equation is discussed. Through the bilinear form of Lax pairs, we prove a generalized Darboux-Crum theorem of the hierarchy. The Bäcklund transformation and the generalized Wronskian solutions are presented. The soliton solutions, explicit rational solutions are obtained then.     

Integrability properties of a generalized reduction of the KdV6 equation

We consider the integrability properties of a generalized version of a similarity reduction of the so-called KdV6 equation, an equation that has recently generated much interest. We give a linear problem for this generalized reduction and show that it satisfies the requirements of the Ablowitz-Ramani-Segur algorithm. In addition we give a Bäcklund transformation to a related equation, giving also an auto-Bäcklund transformation for this last. Our results mirror those for the Korteweg-de Vries equation itself, which has a similarity reduction to an ordinary differential equation which is related by a Bäcklund transformation to the second Painlevé equation, this last having an auto-Bäcklund transformation.     

Homoclinic Orbits for a Perturbed Lattice Modified KdV Equation

We establish the splitting of homoclinic orbits for a near-integrable lattice modified KdV (mKdV) equation with periodic boundary conditions. We use the Bäcklund transformation to construct homoclinic orbits of the lattice mKdV equation. We build the Melnikov function with the gradient of the invariant defined through the discrete Floquet discriminant evaluated at critical points. The criteria for the persistence of homoclinic solutions of the perturbed lattice mKdV equation are established.     

Several kinds of Bäcklund transformations of the cylindrical KdV equation which contains a zero degree termf(t)

By means of discussing the Painleve property of partial differential equations, we obtain the Lax pairs of the cylinder KdV equations with 0-th order term and some classes of Bäcklund transformations, and show that, when the 0-th order term disappears, the Bäcklund transformation of the concerned equation will then degenerate to the Bäcklund transformation of cylinder KdV equation. At the end of this paper several concrete examples are given.Project supported by the Science Fund of the Chinese Academy of Sciences.     

Soliton solutions, Bäcklund transformation and Wronskian solutions for the extended (2+1)-dimensional Konopelchenko-Dubrovsky equations in fluid mechanics

This paper is to investigate the extended (2+1)-dimensional Konopelchenko-Dubrovsky equations, which can be applied to describing some phenomena in the stratified shear flow, the internal and shallow-water waves and plasmas. Bilinear-form equations are transformed from the original equations and N-soliton solutions are derived via symbolic computation. Bilinear-form Bäcklund transformation and single-soliton solution are obtained and illustrated. Wronskian solutions are constructed from the Bäcklund transformation and single-soliton solution.     

Symbolic computation, Bäcklund transformation and analytic N-soliton-like solution for a nonlinear Schrödinger equation with nonuniformity term from certain space/laboratory plasmas

With symbolic computation, a bilinear Bäcklund transformation is presented for a nonlinear Schrödinger equation with nonuniformity term from certain space/laboratory plasmas, and correspondingly the one-soliton-like solution is derived from the Bäcklund transformation. Simultaneously, the N-soliton-like solution in double Wronskian form is also given. Besides, the authors verify that the (N−1)- and N-soliton-like solutions satisfy the Bäcklund transformation. The results obtained in this paper might be valuable for the study of the nonuniform media.     

A vector potential KdV equation and vector Ito equation: soliton solutions, bilinear Bäcklund transformations and Lax pairs

A vector potential KdV equation and vector Ito equation are proposed based on their bilinear forms. Soliton solutions expressed by Pfaffians are obtained. Bilinear Bäcklund transformations and the corresponding Lax pairs for the vector potential KdV equation and the vector Ito equation are derived.     

Superposition formulae of a fifth order KdV equation and its modified equation

The Bäcklund transformation (BT) for a fifth order KdV equation is presented in the bilinear form. Furthermore, a nonlinear superposition formula related to the BT obtained above is proved rigorously. By the way, a nonlinear superposition formula of a modified fifth order KdV equation is also given.     

Pfaffian solutions to a (3+1)-dimensional generalized B-type Kadomtsev-Petviashvili equation and its modified counterpart

A class of exact Pfaffian solutions to a (3+1)-dimensional generalized B-type Kadomtsev-Petviashvili equation is obtained. A set of sufficient conditions consisting of systems of linear partial differential equations involving free parameters is generated to guarantee that the Pfaffian solves the equation. A Bäcklund transformation of the equation is presented. The equation is transformed into a set of bilinear equations, and a few classes of traveling wave solutions, rational solutions and Pfaffian solutions to the extended bilinear equations are furnished. Examples of the Pfaffian solutions are explicitly computed, and a few solutions are plotted.     

The decay mode solutions for the cylindrical KP equation

The decay mode solutions for the cylindrical Kadomtsev-Petviashvili equation can be obtained by the Bäcklund transformation and Hirota method.     

Integrability of a coupled KdV system: Painlevé property, Lax pair and Bäcklund transformation

The integrability of a coupled KdV system is studied by prolongation technique and singularity analysis. As a result, Bäcklund transformation and linear spectral problem associated with this system are obtained. Some special solutions of the system are also proposed.     

Bäcklund transformation and multi-soliton solutions for a (2 + 1)-dimensional Korteweg-de Vries system via symbolic computation

In this paper, the (2 + 1)-dimensional Korteweg-de Vries system is symbolically investigated. By the bilinear method, the N-soliton solution is presented. Then, based on the Bäcklund transformation in bilinear form, a new Bäcklund transformation is obtained and new representation of the N-soliton solution is derived. A class of novel multi-soliton solutions are obtained by the new Bäcklund transformation and the availability of symbolic computation is demonstrated.     

2D Toda lattice equation with self-consistent sources: Casoratian type solutions,bilinear Bäcklund transformation and Lax pair

The two-dimensional Toda lattice equation with self-consistent sources is proposed based on its bilinear forms. Casoratian-type solutions and Bäcklund transformation (BT) for the bilinear forms are presented. Starting from the BT, a Lax pair is derived for the 2D Toda lattice with self-consistent sources.     

Bäcklund transformations and abundant exact explicit solutions of the Sharma-Tasso-Olver equation

By using an extension of the homogeneous balance method and Maple, the Bäcklund transformations for the Sharma-Tasso-Olver equation are derived. The connections between the Sharma-Tasso-Olver equation and some linear partial differential equations are found. With the aid of the transformations given here and the computer program Maple 12, abundant exact explicit special solutions to the Sharma-Tasso-Olver equation are constructed. In addition to all known solutions re-deriving in a systematic way, several entirely new and more general exact explicit solitary wave solutions can also be obtained. These solutions include (a) the algebraic solitary wave solution of rational function, (b) single-soliton solutions, (c) double-soliton solutions, (d) N-soliton solutions, (e) singular traveling solutions, (f) the periodic wave solutions of trigonometric function type, and (g) many non-traveling solutions. By using the Airy’s function and the Bäcklund transformations obtained here, the exact explicit solution of the initial value problem for the STO equation is presented. The variety of the structure of the solutions for the Sharma-Tasso-Olver equation is illustrated.     

On some aspects of Bäcklund transformations

The Painlevé differential equations (P₂-P₆) possess Bäcklund transformations which relate one solution to another solution either of the same equation, with different values of the parameters, or another such equation. We review a method for deriving difference equations, the discrete Painlevé equations in particular, from Bäcklund transformations of the continuous Painlevé equations. Then, we prove the existence of an algebraic formula relating three inconsecutive solutions of the same Bäcklund hierarchy for P₃ and P₄.     

Some types of solutions and generalized binary Darboux transformation for the mKP equation with self-consistent sources

In this paper, an mKP equation with self-consistent sources (mKPESCSs) is structured in the framework of the constrained mKP equation. Based on the conjugate Lax pairs, we construct the generalized binary Darboux transformation and the N-times repeated Darboux transformation with arbitrary functions at time t for the mKPESCSs which offers a non-auto-Bäcklund transformation between two mKPESCSs with different degrees of sources. With the help of these transformations, some new solutions for the mKPESCSs such as soliton solutions, rational solutions, breather type solutions and exponential solutions are found by taking the special initial solution for auxiliary linear problems and the special functions of t-time.     

Darboux and Bäcklund transformations of the bidirectional Sawada-Kotera equation

Darboux and Bäcklund transformations of the bidirectional Sawada-Kotera equation are derived with the help of the resulting Riccati equation. As an application, some explicit solutions of the bidirectional Sawada-Kotera equation are obtained, including rational solutions, periodic solutions, and soliton solutions.     

Bilinear Bäcklund transformation and Lax pair for a coupled Ramani equation

In this paper, a coupled Ramani equation is proposed. The bilinear Bäcklund transformation and Lax pair for this equation are derived starting from its bilinear form. Multisoliton solutions to the system can also be obtained.     

A study on the bilinear Caudrey-Dodd-Gibbon equation

In this paper we consider the Hirota transformation of the Caudrey-Dodd-Gibbon equation (CDGE) from another point of view. As a result, the local equivalence between the CDGE and its bilinear equation is established, and a new type of Bäcklund transformation, which is defined by a second-order ODE along with the appropriate initial values, is presented to construct new solutions for the bilinear CDGE from the seed solutions of original CDGE.     

Bäcklund transformation in bilinear form for a higher-order nonlinear Schrödinger equation

Bäcklund transformation in bilinear form is presented for a higher-order nonlinear Schrödinger equation, which describes the propagation of ultrashort light pulses in optical fibers. With symbolic computation and starting from the Bäcklund transformation, the analytical soliton solution is obtained from a trivial solution and the inverse scattering transform scheme is also derived. Furthermore, the N$N$-soliton solution in double Wronskian form is given, and the value of the arbitrary constant appearing in the Bäcklund transformation is determined for a transformation between the (N−1)$(N-1)$ and N$N$-soliton solutions. The results obtained from the Bäcklund transformation might be valuable in optical communications.