bi-Hamiltonian Formulation Research Articles

Symplectic realizations and symmetries of a Lotka-Volterra type system

In this paper a Lotka-Volterra type system is considered. For such a system, bi-Hamiltonian formulation, symplectic realizations and symmetries are presented.

Hamiltonian structures for the Ostrovsky–Vakhnenko equation

We obtain a bi-Hamiltonian formulation for the Ostrovsky–Vakhnenko (OV) equation using its higher order symmetry and a new transformation to the Caudrey–Dodd–Gibbon–Sawada–Kotera equation. Central to this derivation is the relation between Hamiltonian structures when dependent and independent variables are transformed.

ADJOINT SYMMETRY CONSTRAINTS AND INTEGRABLE COUPLING SYSTEM OF MULTICOMPONENT KN EQUATIONS

A soliton hierarchy of multicomponent KN equations is generated from an arbitrary order matrix spectral problem, along with its bi-Hamiltonian formulation. Adjoint symmetry constraints are presented to manipulate binary nonlinearization for the associated arbitrary order matrix spectral problem. Finally, a class of integrable coupling systems of the multicomponent KN soliton equation hierarchy is obtained using Ma's method associated with enlarging spectral problems [W. X. Ma, Phys. Lett. A316, 72–76 (2003)].

A three-parameter difference Hamiltonian operator, corresponding pair of Hamiltonian operators and a family of Liouville integrable lattice equations

A difference Hamiltonian operator involved three arbitrary real parameters is introduced. When these parameters in the difference Hamiltonian operator are properly chosen, we obtain a pair of difference Hamiltonian operators. Then, using Magri scheme of bi-Hamiltonian formulation, we construct a family of Liouville integrable lattice equations. Finally, the discrete zero curvature representation of obtained family is presented.

Adjoint symmetry constraints of the vector KN equations and their integrable coupling system

In this paper we present a soliton hierarchy of vector KN (Kaup–Newell) equations by using an arbitrary order matrix spectral problem, along with its bi-Hamiltonian formulation. Then, adjoint symmetry constraints are presented for manipulating binary nonlinearization for the associated arbitrary order matrix spectral problem. The resulting spatial and temporal constrained flows are shown to provide integrable decompositions of the vector KN equations. Finally, a class of integrable coupling systems of the vector KN soliton equations is obtained through enlarging the spectral problem.

On the N=2 supersymmetric Camassa–Holm and Hunter–Saxton equations

We consider N=2 supersymmetric extensions of the Camassa–Holm and Hunter–Saxton equations. We show that they admit geometric interpretations as Euler equations on the superconformal algebra of contact vector fields on the 1∣2-dimensional supercircle. We use the bi-Hamiltonian formulation to derive Lax pairs. Moreover, we present some simple examples of explicit solutions. As a by-product of our analysis, we obtain a description of the bounded traveling-wave solutions for the two-component Hunter–Saxton equation.

Group-invariant soliton equations and bi-Hamiltonian geometric curve flows in Riemannian symmetric spaces

Universal bi-Hamiltonian hierarchies of group-invariant (multicomponent) soliton equations are derived from non-stretching geometric curve flows γ ( t , x ) in Riemannian symmetric spaces M = G / H , including compact semisimple Lie groups M = K for G = K × K , H = diag G . The derivation of these soliton hierarchies utilizes a moving parallel frame and connection 1-form along the curve flows, related to the Klein geometry of the Lie group G ⊃ H where H is the local frame structure group. The soliton equations arise in explicit form from the induced flow on the frame components of the principal normal vector N = ∇ x γ x along each curve, and display invariance under the equivalence subgroup in H that preserves the unit tangent vector T = γ x in the framing at any point x on a curve. Their bi-Hamiltonian integrability structure is shown to be geometrically encoded in the Cartan structure equations for torsion and curvature of the parallel frame and its connection 1-form in the tangent space T γ M of the curve flow. The hierarchies include group-invariant versions of sine–Gordon (SG) and modified Korteweg–de Vries (mKdV) soliton equations that are found to be universally given by curve flows describing non-stretching wave maps and mKdV analogs of non-stretching Schrödinger maps on G / H . These results provide a geometric interpretation and explicit bi-Hamiltonian formulation for many known multicomponent soliton equations. Moreover, all examples of group-invariant (multicomponent) soliton equations given by the present geometric framework can be constructed in an explicit fashion based on Cartan’s classification of symmetric spaces.

EXPLICIT SOLUTIONS TO THE KAUP–KUPERSHMIDT EQUATION VIA NONLOCAL SYMMETRIES

The fifth order Kaup–Kupershmidt equation [Formula: see text] is a most important example of an integrable partial differential equation. Among other properties, it is integrable via scattering/inverse scattering techniques, it admits a bi-Hamiltonian formulation, and it possesses an infinite number of generalized symmetries. In sharp contrast with other integrable equations, however, it has proven very difficult to exhibit explicit solutions to Kaup–Kupershmidt. In this paper, we present several interesting particular solutions to this equation obtained with the help of nonlocal symmetries.

On dispersionless Lax representations for two-primary models

The equivalence between bi-Hamiltonian formulation and Lax representation of dispersionless integrable hierarchies associated with two-primary models of Frobenius manifolds is explicitly verified.

Polytropic gas dynamics revisited

We investigate the Hamiltonian as well as Lax formulations of the polytropic gas dynamics which can be characterized by the polytropic exponent γ=1+h. We show that when h=1∕m with ∣m∣∊N⩾2, the resonant phenomena occur in bi-Hamiltonian formulation and logarithmic-type conserved charges emerge naturally. We provide a logarithmic Lax representation for conserved charges and the whole hierarchy flows, which coincides with the bi-Hamiltonian formulation constructed from a two-dimensional Frobenius manifold associated with the polytropic gas dynamics.

The extended bigraded Toda hierarchy

We generalize the Toda lattice hierarchy by considering N+M dependent variables. We construct roots and logarithms of the Lax operator which are uniquely defined operators with coefficients that are $\epsilon$-series of differential polynomials in the dependent variables, and we use them to provide a Lax pair definition of the extended bigraded Toda hierarchy. Using R-matrix theory we give the bihamiltonian formulation of this hierarchy and we prove the existence of a tau function for its solutions. Finally we study the dispersionless limit and its connection with a class of Frobenius manifolds on the orbit space of the extended affine Weyl groups of the $A$ series.

Integrable dispersionless KdV hierarchy with sources

An integrable dispersionless KdV hierarchy with sources (dKdVHWS) is derived. Lax pair equations and bi-Hamiltonian formulation for dKdVHWS are formulated. Hodograph solution for the dispersionless KdV equation with sources (dKdVWS) is obtained via hodograph transformation. Furthermore, the dispersionless Gelfand-Dickey hierarchy with sources (dGDHWS) is presented.

BIDIFFERENTIAL CALCULI, BICOMPLEX STRUCTURE AND ITS APPLICATION TO BIHAMILTONIAN SYSTEMS

In this exposition, we study the relationship between the bihamiltonian formalism of completely integrable systems using the bidifferential calculi introduced by Dimakis and Müller-Hoissen in [1] and the bihamiltonian formulation of integrable systems with a finite number of degrees of freedom via the Frölicher–Nijenhuis geometry. This pair of bidifferetial operators are used to construct alternative Lie algebroids as shown by Camacaro and Carinena. We find its connection to Finsler geometry. We also find the dispersionless integrable hierarchies using the bidifferential ideals. Finally, we lay out its connection to Gelfand–Zakharevich bihamiltonian geometry.

Recursion operators and bi-Hamiltonian formulations of the Landau–Lifshitz equation hierarchies

Using a polynomial pencil of Lax pairs we give a new bi-Hamiltonian formulation for the Landau–Lifshitz equation hierarchy and find a new recursion operator related to it.

Bi-Hamiltonian systems of deformation type

In this paper, after some recalls about Poisson cohomology, we first study what the general method is in order to obtain a bi-Hamiltonian formulation of a given Hamiltonian system by means of a deformation. Then we show that the bi-Hamiltonian formulation which results from the deformation of a Poisson structure by means of a suitable non-Noether symmetry cannot explain the complete integrability for a large class of Arnold–Liouville integrable systems; next we prove that the deformation must be made in this context by a suitable mastersymmetry. At last, we give several examples.

A Difference Hamiltonian Operator and a Hierarchy ofGeneralized Toda Lattice Equations

A difference Hamiltonian operator with three arbitraryconstants is presented. When the arbitrary constants in the Hamiltonianoperator are suitably chosen, a pair of Hamiltonian operators are given. Theresulting Hamiltonian pair yields a difference hereditary operator. UsingMagri scheme of bi-Hamiltonian formulation, a hierarchy of the generalizedToda lattice equations is constructed. Finally, the discrete zero curvaturerepresentation is given for the resulting hierarchy.

Positive and Negative Hierarchies of Integrable Lattice Models Associated with a Hamiltonian Pair

A difference Hamiltonian operator involving two arbitrary constants is presented, and it is used to construct a pair of nondegenerate Hamiltonian operators. The resulting Hamiltonian pair yields two difference hereditary operators, and the associated positive and negative hierarchies of nonlinear integrable lattice models are derived through the bi-Hamiltonian formulation. Moreover, the two lattice hierarchies are proved to have discrete zero curvature representations associated with a discrete spectral problem, which also shows that the positive and negative hierarchies correspond to positive and negative power expansions of Lax operators with respect to the spectral parameter, respectively. The use of zero curvature equation leads us to conclude that all resulting integrable lattice models are local and that the integrable lattice models in the positive hierarchy are of polynomial type and the integrable lattice models in the negative hierarchy are of rational type.

Generalized fermionic discrete Toda hierarchy

We describe bi‐Hamiltonian structure and Lax‐pair formulation with the spectral parameter of the generalized fermionic Toda lattice hierarchy as well as its bosonic and fermionic symmetries for different (including periodic) boundary conditions. Its two reductions N = 4 and N = 2 supersymmetric Toda lattice hierarchies in different (including canonical) bases are investigated. Its r‐matrix description, monodromy matrix, and spectral curves are discussed.

Gaudin models and bending flows: a geometrical point of view

In this paper we discuss the bihamiltonian formulation of the (rational XXX) Gaudin models of spin-spin interaction, generalized to the case of sl(r)-valued spins. In particular, we focus on the homogeneous models. We find a pencil of Poisson brackets that recursively define a complete set of integrals of the motion, alternative to the set of integrals associated with the 'standard' Lax representation of the Gaudin model. These integrals, in the case of su(2), coincide wih the Hamiltonians of the 'bending flows' in the moduli space of polygons in Euclidean space introduced by Kapovich and Millson. We finally address the problem of separability of these flows and explicitly find separation coordinates and separation relations for the r=2 case.

Supersymmetric extensions of the Harry Dym hierarchy

We study the supersymmetric extensions of the Harry Dym hierarchy of equations. We obtain the susy-B extension, the doubly susy-B extension as well as the N=1 and the N=2 supersymmetric extensions for this system. The N=2 supersymmetric extension is particularly interesting, since it leads to new classical integrable systems in the bosonic limit. We prove the integrability of these systems through the bi-Hamiltonian formulation of integrable models and through the Lax description. We also discuss the supersymmetric extension of the Hunter–Zheng equation which belongs to the Harry Dym hierarchy of equations.