Bäcklund Transformations for the Camassa–Holm Equation

The Bäcklund transformation (BT) for the Camassa–Holm (CH) equation is presented and discussed. Unlike the vast majority of BTs studied in the past, for CH the transformation acts on both the dependent and (one of) the independent variables. Superposition principles are given for the action of double BTs on the variables of the CH and the potential CH equations. Applications of the BT and its superposition principles are presented, specifically the construction of travelling wave solutions, a new method to construct multisoliton, multicuspon and soliton–cuspon solutions, and a derivation of generating functions for the local symmetries and conservation laws of the CH hierarchy.     

Bäcklund Transformations for the One-Dimensional Schrödinger Equation

Journal of Applied and Industrial Mathematics - We study the system of equations which bases on the one-dimensional Schrödinger equation and connects the potential, amplitude, and phase...     

Bäcklund Transformation and Dressing Chains for the Landau–Lifshitz Equation

We use the dressing method for the Landau–Lifshitz equation and the breeding procedure to obtain a modified Landau–Lifshitz equation. We find the Darboux transformation (the dressing) for the integrable Landau–Lifshitz equation of the anisotropic magnet. We find the Bäcklund transformations and dressing chains.     

Some Local Properties of Bäcklund Transformations

For Bäcklund transformations, treated as relations in the categoryof diffieties, local conditions of effectivity and normality are introduced,having implications for the solution generating properties. We check themfor the pKdV, the sine-Gordon, and the Tzitzéica equation.     

Lagrangian Chains and Canonical Bäcklund Transformations

We consider Darboux transformations for operators of arbitrary order and construct the general theory of Bäcklund transformations based on the Lagrangian formalism. The dressing chain for the Boussinesq equation and its reduction are demonstrative examples for the suggested general theory. We also discuss the well-known Bäcklund transformations for classical soliton equations.     

Unfamiliar Aspects of Bäcklund Transformations and an Associated Degasperis–Procesi Equation

We summarize the results of our recent work on Bäcklund transformations (BTs), particularly focusing on the relation between BTs and infinitesimal symmetries. We present a BT for an associated Degasperis–Procesi (aDP) equation and its superposition principle and investigate the solutions generated by applying this BT. Following our general methodology, we use the superposition principle of the BT to generate the infinitesimal symmetries of the aDP equation.     

Bäcklund transformations for the nonholonomic Veselova system

We present auto and hetero Bäcklund transformations of the nonholonomic Veselova system using standard divisor arithmetic on the hyperelliptic curve of genus two. As a by-product one gets two natural integrable systems on the cotangent bundle to the unit two-dimensional sphere whose additional integrals of motion are polynomials in the momenta of fourth order.     

Bäcklund transformation and applications for the Vakhnenko equation

Theoretical and Mathematical Physics - With the aid of the reciprocal transformation and the associated Vakhnenko equation, we construct and study a Bäcklund transformation (BT) involving both...     

Bäcklund transformations for the Jacobi system on an ellipsoid

We consider analogues of auto- and hetero-Bäcklund transformations for the Jacobi system on a threeaxis ellipsoid. Using the results in a Weierstrass paper, where the change of times reduces integrating the equations of motion to inverting the Abel mapping, we construct the differential Abel equations and auto-Bäcklund transformations preserving the Poisson bracket with respect to which the equations of motion written in the Weierstrass form are Hamiltonian. Transforming this bracket to the canonical form, we can construct a new integrable system on the ellipsoid with a Hamiltonian of the natural form and with a fourth-degree integral of motion in momenta.     

Nonlinear Evolution Equations: B?cklund Transformations and B?cklund Charts

B?cklund Charts have been introduced to depict links, via B?cklund Transformations, which relate different Nonlinear Evolution Equations. Notably, the links established among different Nonlinear Evolution Equations can be extended to the whole Hierarchies of Nonlinear Evolution Equations. This approach proved to be very fruitful, as well known, when applied to scalar Nonlinear Evolution Equations since it induces very many interesting results. Some of them are here reviewed and further new research perspectives are shown. Specifically, when the non commutative analogue Nonlinear Evolution Equations are introduced new problems arise. Here, hierarchies of non-commutative Nonlinear Evolution Equations together with their links via B?cklund Transformations are considered. Specifically, a non-commutative analogues of Cole-Hopf and of Miura transformation are shown, respectively, to connect the operator versions of Burgers equation to heat equation and the operator version of KdV equation to the corresponding operator version of modified KdV equation. Again, the links are connecting not only the base member equations but all the corresponding equations in the hierarchy generated by the recursion operator it admits. Finally, it is pointed out how the method here presented allows to construct new non-commutative operator equation.     

Bäcklund transformations

We describe a Bäcklund transformation, i.e., a differentially related pair of differential equations, in a coordinate manner appropriate for calculations and applications. We present several known explanatory examples, including Bäcklund transformations for gauge fields in a Minkowski space of arbitrary dimension.     

Symmetry Reduction of Exterior Differential Systems and B?cklund Transformations for PDE in the Plane

We approach the construction of B?cklund transformations for Darboux integrable hyperbolic partial differential equations in the plane through the reduction of exterior differential systems.     

Bäcklund transformations for the difference Hirota equation and the supersymmetric Bethe ansatz

We consider GL(K|M)-invariant integrable supersymmetric spin chains with twisted boundary conditions and demonstrate the role of Bäcklund transformations in solving the difference Hirota equation for eigenvalues of their transfer matrices. We show that the nested Bethe ansatz technique is equivalent to a chain of successive Bäcklund transformations “undressing” the original problem to a trivial one.     

Abel’s theorem and Bäcklund transformations for the Hamilton-Jacobi equations

We consider an algorithm for constructing auto-Bäcklund transformations for finitedimensional Hamiltonian systems whose integration reduces to the inversion of the Abel map. In this case, using equations of motion, one can construct Abel differential equations and identify the sought Bäcklund transformation with the well-known equivalence relation between the roots of the Abel polynomial. As examples, we construct Bäcklund transformations for the Lagrange top, Kowalevski top, and Goryachev–Chaplygin top, which are related to hyperelliptic curves of genera 1 and 2, as well as for the Goryachev and Dullin–Matveev systems, which are related to trigonal curves in the plane.     

Bäcklund maps and Lie–Bäcklund transformations as differential-geometric structures

This paper is an exposition of the author’s report prepared for the International Conference devoted to the centennial anniversary of G. F. Laptev (Laptev seminar–2009). In the first section, we consider Bäcklund transformations of second-order partial differential equations. In the present work, the theory of Bäcklund transformations is treated as a special branch of the theory of connections. The second section is devoted to differential-geometric structures generated by the so-called Lie–Bäcklund transformations (or, equivalently, contact transformations of higher order) that are a special case of diffeomorphisms between the manifolds of holonomic jets. Recall that it was G. F. Laptev who pointed out the possibility of considering differentiable mappings as differential-geometric structures.     

Bäcklund transformations for new fourth Painlevé hierarchies

We consider a system of equations defined using the Hamiltonian operator of the Boussinesq hierarchy, as well as two successive modifications thereof. We are able to reduce the order of these three systems and give Bäcklund transformations between the integrated equations. We also give auto-Bäcklund transformations for the two modified systems.Particular cases of two of the three equations considered correspond to generalized fourth Painlevé hierarchies and are new; these are particular cases of the two modified systems. Thus we obtain auto-Bäcklund transformations for these new fourth Painlevé hierarchies, as well as Bäcklund transformations between our hierarchies. Our results on reduction of order are also applicable in this special case, and include as a particular example a reduction of order for the scaling similarity reduction of the Boussinesq equation, a result which, remarkably, seems not to have been given previously.     

On a direct procedure for the disclosure of Lax pairs and Bäcklund transformations

A direct and unifying scheme for the disclosure of bilinear Bäcklund transformations and linear Lax systems associated with soliton equations is presented. The scheme is based on a concept of scale invariance and on the use of a class of partitional polynomials: the binary Bell polynomials. The applicability of the procedure is tested on a variety of soliton equations.