# Journal of Nonlinear Mathematical Physics

1499 articles

**Research Article**

## Quantization of the dynamics of a particle on a double cone by preserving Noether symmetries

G. Gubbiotti, M.C. Nucci

Pages: 356 - 367

The classical quantization of the motion of a free particle and that of an harmonic oscillator on a double cone are achieved by a quantization scheme [M. C. Nucci, Theor. Math. Phys. 168 (2011) 994], that preserves the Noether point symmetries of the underlying Lagrangian in order to construct the Schrödinger...

**Research Article**

## Discrete Multiscale Analysis: A Biatomic Lattice System

G. A. Cassatella Contra, D. Levi

Pages: 357 - 377

We discuss a discrete approach to the multiscale reductive perturbative method and apply it to a biatomic chain with a nonlinear interaction between the atoms. This system is important to describe the time evolution of localized solitonic excitations.
We require that also the reduced equation be discrete....

**Research Article**

## Elastic null curve flows, nonlinear *C*-integrable systems, and geometric realization of Cole-Hopf transformations

Zühal Küçükarslan Yüzbaşı, Stephen C. Anco

Pages: 357 - 392

Elastic (stretching) flows of null curves are studied in three-dimensional Minkowski space. As a main tool, a natural type of moving frame for null curves is introduced, without use of the pseudo-arclength. This new frame is related to a Frenet null frame by a gauge transformation that belongs to the...

**Research Article**

## Symmetric solutions to the four dimensional degenerate Painlevé type equation *NY*^{A4}

Kazuo Kaneko

Pages: 357 - 370

We have classified symmetric solutions around the origin to the four dimensional degenerate Painlevé type equation NYA4 with generic values of parameters. We obtained sixteen meromorphic solutions, which are transformed each other by the Bäcklund transformation. We calculated the linear monodromy for...

**Research Article**

## Superalgebras for the 3D Harmonic Oscillator and Morse Quantum Potentials

H. Fakhri

Pages: 361 - 375

In addition to obtaining supersymmetric structure related to the partner Hamiltonans, we get another supersymmetric structure via factorization method for both the 3D harmonic oscillator and Morse quantum potentials. These two supersymmetries induce also an additional supersymmetric structure involving...

**Research Article**

## Search for CAC-integrable homogeneous quadratic triplets of quad equations and their classification by BT and Lax

Jarmo Hietarinta

Pages: 358 - 389

We consider two-dimensional lattice equations defined on an elementary square of the Cartesian lattice and depending on the variables at the corners of the quadrilateral. For such equations the property often associated with integrability is that of “multidimensional consistency” (MDC): it should be...

**Research Article**

## Invariant functions and contractions of certain types of Lie algebras of lower dimensions

J.M. Escobar, J. Núñez, P. Pérez-Fernández

Pages: 358 - 374

In this paper, we deal with contractions of Lie algebras. We use two invariant functions of Lie algebras as a tool, named ψ and φ function, respectively, which have a great application in Physics due to their remarkable properties. We focus the study of these functions in the frame of the filiform Lie...

**Research Article**

## Symmetry Preserving Discretization of SL(2,R) Invariant Equations

Anne Bourlioux, Raphaël Rebelo, Pavel Winternitz

Pages: 362 - 372

Nonlinear ODEs invariant under the group SL(2,R) are solved numerically. We show that solution methods incorporating the Lie point symmetries provide better results than standard methods.

**Research Article**

## Reductions of Integrable Lattices

B. Grammaticos, A. Ramani, J. Satsuma, R. Willox

Pages: 363 - 371

We present a novel method for the reduction of integrable two-dimensional discrete systems to one-dimensional mappings. The procedure allows for the derivation of nonautonomous systems, which are typically discrete (difference or q) Painlevé equtions, or of autonomous ones. In the latter case we produce...

**Research Article**

## Dark Equations

B.A. Kupershmidt

Pages: 363 - 445

Observing the Universe, astronomers have concluded that the motion of stars can not be accounted for unless one assumes that most of the mass in the Universe is carried on by a "dark matter", so far impervious to all attempts at being detected. There is now a similar concept of "dark energy". I shall...

**Research Article**

## Differential Constraints Compatible with Linearized Equations

Ahmet Satir

Pages: 364 - 370

Differential constraints compatible with the linearized equations of partial differential equations are examined. Recursion operators are obtained by integrating the differential constraints.

**Research Article**

## The Cohomology of the Variational Bicomplex Invariant under the Symmetry Algebra of the Potential Kadomtsev-Petviashvili Equation

Juha Pohjanpelto

Pages: 364 - 376

The variational bicomplex of forms invariant under the symmetry algebra of the potential Kadomtsev-Petviashvili equation is described and the cohomology of the associated Euler-Lagrange complex is computed. The results are applied to a characterization problem of the Kadomtsev-Petviashvili equation by...

**Research Article**

## A generalized Schrödinger equation via a complex Lagrangian of electrodynamics

Nicoleta Aldea, Gheorghe Munteanu

Pages: 361 - 373

In this paper we give a generalized form of the Schrödinger equation in the relativistic case, which contains a generalization of the Klein-Gordon equation. By complex Legendre transformation, the complex Lagrangian of electrodynamics produces a complex relativistic Hamiltonian H of electrodynamics,...

**Research Article**

## Feynman-Jackson integrals

Rafael Díaz, Eddy Pariguan

Pages: 365 - 376

We introduce perturbative Feynman integrals in the context of q-calculus generalizing the Gaussian q-integrals introduced by Diaz and Teruel. We provide analytic as well as combinatorial interpretations for the Feynman-Jackson integrals.

**Research Article**

## Poisson Homology of r-Matrix Type Orbits I: Example of Computation

Alexei Kotov

Pages: 365 - 383

In this paper we consider the Poisson algebraic structure associated with a classical r-matrix, i.e. with a solution of the modified classical YangBaxter equation. In Section 1 we recall the concept and basic facts of the r-matrix type Poisson orbits. Then we describe the r-matrix Poisson pencil (i.e...

**Research Article**

## Solutions of some second order ODEs by the extended Prelle-Singer method and symmetries

A. Ghose Choudhury, Partha Guha, Barun Khanra

Pages: 365 - 382

In this paper we compute first integrals of nonlinear ordinary differential equations using the extended Prelle-Singer method, as formulated by Chandrasekar et al in J. Math. Phys. 47 (2), 023508, (2006). We find a new first integral for the Painlev´e-Gambier XXII equation. We also derive the first integrals...

**Research Article**

## Lie Algebras and Superalgebras Defined by a Finite Number of Relations: Computer Analysis

V.P. Gerdt, V.V. Kornyak

Pages: 367 - 373

The presentation of Lie (super)algebras by a finite set of generators and defining relations is one of the most general mathematical and algorithmic schemes of their analysis. It is very important, for instance, for investigation of the particular Lie (super)algebras arising in different (super)symmetric...

**Research Article**

## Exact Solutions of the Modified Gross–Pitaevskii Equation in “Smart“ Periodic Potentials in the Presence of External Source

Thokala Soloman Raju, Prasanta K. Panigrahi

Pages: 367 - 376

We report wide class of exact solutions of the modified Gross–Pitaevskii equation (GPE) in “smart” Jacobian elliptic potentials, in the presence of external source. Solitonlike solutions, singular solutions, and periodic solutions are found using a recently developed fractional transform in which all...

**Research Article**

## Solving Simultaneously Dirac and Ricatti Equations

J. Casahorrán

Pages: 371 - 382

We analyse the behaviour of the Dirac equation in d = 1 + 1 with Lorentz scalar potential. As the system is known to provide a physical realization of supersymmetric quantum mechanics, we take advantage of the factorization method in order to enlarge the restricted class of solvable problems. To be precise,...

**Research Article**

## Factorisation of recursion operators of some Lagrangian systems

Dmitry K. Demskoi

Pages: 368 - 378

We observe that recursion operator of an S-integrable hyperbolic equation that degenerates into a Liouvile-type equation admits a particular factorisation. This observation simplifies the construction of such operators. We use it to find a new quasi-local recursion operator for a triplet of scalar fields....

**Research Article**

## Bi-Hamiltonian structure of the extended noncommutative Toda hierarchy

Chuanzhong Li, Tao Song

Pages: 368 - 382

The noncommutative Toda hierarchy is studied with the help of Moyal deformation by a reduction on the non-commutative two dimensional Toda hierarchy. Further we generalize the noncommutative Toda hierarchy to the extended noncommutative Toda hierarchy. To survey on its integrability, we construct the...

**Research Article**

## Link Invariants and Lie Superalgebras

P. Grozman, D. Leites

Pages: 372 - 379

Berger and Stassen reviewed skein relations for link invariants coming from the simple Lie algebras g. They related the invariants with decomposition of the tensor square of the g-module V of minimal dimension into irreducible components. (If V V , one should also consider the decompositions of V V and...

**Research Article**

## Symmetries of the Relativistic Two-Particle Model with Scalar-Vector Interaction

Askold Duviryak

Pages: 372 - 378

A relativistic two-particle model with superposition of time-asymmetric scalar and vector interactions is proposed and its symmetries are considered. It is shown that first integrals of motion satisfy nonlinear Poisson-bracket relations which include the Poincaré algebra and one of the algebras so(1,3),...

**Research Article**

## New Quasi-Exactly Solvable Difference Equation

Ryu Sasaki

Pages: 373 - 384

Exact solvability of two typical examples of the discrete quantum mechanics, i.e. the dynamics of the Meixner-Pollaczek and the continuous Hahn polynomials with full parameters, is newly demonstrated both at the SchrÂ¨odinger and Heisenberg picture levels. A new quasiexactly solvable difference equation...

**Research Article**

## Galilean-invariant Nonlinear PDEs and their Exact Solutions

Roman M. Cherniha

Pages: 374 - 383

All systems of (n+1)-dimensional quasilinear evolutional second- order equations invariant under the chain of algebras AG(1.n) AG1(1.n) AG2(1.n) are described. The obtained results are illustrated by examples of nonlinear Schrödinger equations.

**Research Article**

*µ* -symmetry and *µ* -conservation law for the extended mKdV equation

Kh. Goodarzi, M. Nadjafikhah

Pages: 371 - 381

In this paper, we obtain µ -symmetry and µ -conservation law of the extended mKdV equation. The extended mKdV equation dose not admit a variational problem since it is of odd order. First we obtain µ -conservation law of the extended mKdV equation in potential form because it admits a variational problem,...

**Research Article**

## A Whittaker-Shannon-Kotelnikov sampling theorem related to the Askey-Wilson functions

Fethi Bouzeffour

Pages: 375 - 388

A Whittaker-Shannon-Kotelâ€™nikov sampling theorem related to the Askey-Wilson functions is proved. Applications to finite continuous Askey-Wilson transform are given.

**Research Article**

## Infinite-Dimensional and Colored Supermanifolds

Vladimir Molotkov

Pages: 375 - 446

Here the theory of finite-dimensional supermanifolds is generalized in two directions.
First, we introduce infinite-dimensional supermanifolds “locally isomorphic” to arbitrary Banach (or, more generally, locally convex) superspaces. This is achieved by considering supermanifolds as functors (equipped...

**Research Article**

## Normal Forms for Coupled Takens-Bogdanov Systems

David Mumo Malonza

Pages: 376 - 398

The set of systems of differential equations that are in normal form with respect to a particular linear part has the structure of a module of equivariants, and is best described by giving a Stanley decomposition of that module. In this paper Groebner basis methods are used to determine a Groebner basis...

**Research Article**

## Geometry of the Recursion Operators for the GMV System

A. B. Yanovski, G. Vilasi

Pages: 373 - 390

We consider the Recursion Operator approach to the soliton equations related to a auxiliary linear system introduced recently by Gerdjikov, Mikhailov and Valchev (GMV system) and their interpretation as dual of Nijenhuis tensors on the manifold of potentials.

**Research Article**

## Cohomology of the Lie Superalgebra of Contact Vector Fields on 𝕂^{1|1} and Deformations of the Superspace of Symbols

Imed Basdouri, Mabrouk Ben Ammar, Nizar Ben Fraj, Maha Boujelbene, Kaouthar Kamoun

Pages: 373 - 409

Following Feigin and Fuchs, we compute the first cohomology of the Lie superalgebra 𝒦(1) of contact vector fields on the (1, 1)-dimensional real or complex superspace with coefficients in the superspace of linear differential operators acting on the superspaces of weighted densities. We also compute...

**Research Article**

## Nonlocal Symmetries and the Complete Symmetry Group of 1 + 1 Evolution Equations

S.M. Myeni, P.G.L. Leach

Pages: 377 - 392

The complete symmetry group of a 1 + 1 linear evolution equation has been demon- strated to be represented by the six-dimensional Lie algebra of point symmetries sl(2, R)?s W , where W is the three-dimensional Heisenberg-Weyl algebra. The infinite number of solution symmetries does not play a role in...

**Research Article**

## On Shtelen's Solution of the Free Linear Schrödinger Equation

W.W. Zachary

Pages: 377 - 382

The solution of the three-dimensional free Schrödinger equation due to W.M. Shtelen based on the invariance of this equation under the Lorentz Lie algebra so(1,3) of nonlocal transformations is considered. Various properties of this solution are examined, including its extension to n 3 spatial dimensions...

**Letter to Editor**

## On some connections between the Gompertz function and special numbers

Grzegorz Rządkowski, Wojciech Rządkowski, Paweł Wójcicki

Pages: 374 - 380

In the present paper we show that the Gompertz function, the Fisher–Tippett and the Gumbel probability distributions are related to both Stirling numbers of the second kind and Bernoulli numbers. Especially we prove for the Gumbel probability density function an analog of the Grosset–Veselov formula...

**Research Article**

## Supersymmetric Sawada-Kotera Equation: Bäcklund-Darboux Transformations and Applications

Hui Mao, Q.P. Liu, Lingling Xue

Pages: 375 - 386

In this paper, we construct a Darboux transformation and the related Bäcklund transformation for the super-symmetric Sawada-Kotera (SSK) equation. The associated nonlinear superposition formula is also worked out. We demonstrate that these are natural extensions of the similar results of the Sawada-Kotera...

**Research Article**

## Relativistic Two-Body Problem: Existence and Uniqueness of Two-Sided Solutions to Functional-Differential Equations of Motion

V.I. Zhdanov

Pages: 379 - 384

We study a class of explicitly Poincare-invariant equations of motion (EMs) of two point bodies with a finite speed of propagation of interactions (combination of retarded and advanced ones) that may be considered as functional-differential equations or differential equations with deviating argument...

**Research Article**

## A Class of Equations with Peakon and Pulson Solutions (with an Appendix by Harry Braden and John Byatt-Smith)

Darryl D. Holm, Andrew N.W. Hone

Pages: 380 - 394

We consider a family of integro-differential equations depending upon a parameter b as well as a symmetric integral kernel g(x). When b = 2 and g is the peakon kernel (i.e. g(x) = exp(-|x|) up to rescaling) the dispersionless Camassa-Holm equation results, while the Degasperis-Procesi equation is obtained...

**Research Article**

## Theory of Economic Equilibrium

Nikolai Gonchar

Pages: 380 - 400

New concepts of economics such as an average demand matrix of society, strategy of a firm and consumer behaviour, and others are introduced. We give sufficient conditions for technological mapping under which there exist both the Walras equlibrium state and optimal Walras equilibrium one. We obtain the...

**Research Article**

## A Large Time Asymptotics for Transparent Potentials for the Novikov–Veselov Equation at Positive Energy

A. V. Kazeykina, R. G. Novikov

Pages: 377 - 400

In the present paper we begin studies on the large time asymptotic behavior for solutions of the Cauchy problem for the Novikov–Veselov equation (an analog of KdV in 2 + 1 dimensions) at positive energy. In addition, we are focused on a family of reflectionless (transparent) potentials parameterized...

**Research Article**

## The Structure of Gelfand-Levitan-Marchenko Type Equations for Delsarte Transmutation Operators of Linear Multi-Dimensional Differential Operators and Operator Pencils. Part 2

Jolanta Golenia, Anatolij K. Prykarpatsky, Yarema A. Prykarpatsky

Pages: 381 - 408

The differential-geometric and topological structure of Delsarte transmutation opertors their associated Gelfand-Levitan-Marchenko type equations are studied making use of the de Rham-Hodge-Skrypnik differential complex. The relationships with spetral theory and special Berezansky type congruence properties...

**Research Article**

## The Transfer Integral Operator Method in the Study of DNA Unzipping and Bubble Formation

Z. Rapti, K. Ø. Rasmussen, A. R. Bishop

Pages: 381 - 396

In this work we reexamine the unzipping and bubble formation of DNA in the context of the Peyrard–Bishop–Dauxois DNA model using the transfer integral operator method. After a brief overview of the method, we use it to calculate the probabilities that consecutive base-pairs are stretched beyond a threshold...

**Research Article**

## The Influence of Quantum Field Fluctuations on Chaotic Dynamics of YangMills System

V.I. Kuvshinov, A.V. Kuzmin

Pages: 382 - 388

On example of the model field system we demonstrate that quantum fluctuations of non-abelian gauge fields leading to radiative corrections to Higgs potential and spontaneous symmetry breaking can generate order region in phase space of inherently chaotic classical field system. We demonstrate on the...

**Research Article**

## Integrability of Certain Deformed Nonlinear Partial Differential Equations

R. Sahadevan, L. Nalinidevi

Pages: 379 - 396

A systematic investigation of certain higher order or deformed soliton equations with (1 + 1) dimensions, from the point of complete integrability, is presented. Following the procedure of Ablowitz, Kaup, Newell and Segur (AKNS) we find that the deformed version of Nonlinear Schrodinger equation, Hirota...

**Research Article**

## Primary Branch Solutions of First Order Autonomous Scalar Partial Differential Equations via Lie Symmetry Approach

S. Y. Lou, Ruo Xia Yao

Pages: 379 - 392

A primary branch solution (PBS) is defined as a solution with m independent n − 1 dimensional arbitrary functions for an m order n dimensional partial differential equation (PDE). PBSs of arbitrary first order scalar PDEs can be determined by using Lie symmetry group approach companying with the introduction...

**Research Article**

## Lie Superalgebra Valued Self-Dual Yang-Mills Fields and Symmetry Reduction

M. Legaré

Pages: 383 - 391

Self-dual Yang-Mills fields with values in a Lie superalgebra on the four-dimensional Euclidean space and pseudo-Euclidean space of signature (2,2) can be reduced by subgroups of the corresponding conformal group to integrable systems with anticommuting degrees of freedom. Examples of reductions are...

**Research Article**

## Symmetry analysis for Whitham-Broer-Kaup equations

Zhiyong Zhang, Xuelin Yong, Yufu Chen

Pages: 383 - 397

We investigate a further group analysis of Whitham-Broer-Kaup(for short WBK) equations. An optimal system of one-dimensional subalgebras is derived and used to construct reduced equations and similarity solutions. Moreover, a special case of WBK equations is linearized and some new solutions are obtained....

**Research Article**

## The Nonabelian Liouville-Arnold Integrability by Quadratures Problem: a Symplectic Approach

Anatoliy K. Prykarpatsky

Pages: 384 - 410

A symplectic theory approach is devised for solving the problem of algebraic-analytical construction of integral submanifold imbeddings for integrable (via the nonabelian Liouville-Arnold theorem) Hamiltonian systems on canonically symplectic phase spaces.

**Research Article**

## Two-Parameter Deformation of the Oscillator Algebra and (p, q)Analog of Two-Dimensional Conformal Field Theory

Ivan Burban

Pages: 384 - 391

The two-parameter deformation of canonical commutation relations is discussed. The self-adjointness property of the (p, q)-deformed position Q and momentum P operators is investigated. The (p, q)-analog of two-dimensional conformal field theory based on the (p, q)-deformation of the su(1, 1) subalgebra...

**Research Article**

## Products of distributions and collision of a *δ*-wave with a *δ′*-wave in a turbulent model

C.O.R. Sarrico, A. Paiva

Pages: 381 - 394

We study the possibility of collision of a δ-wave with a stationary δ′-wave in a model ruled by equation f (t)ut+[u2−β(x−γ(t))u]x = 0, where f, β and γ are given real functions and u = u(x, t) is the state variable. We adopt a solution concept which is a consistent extension of the classical solution...

**Short Communication**

## Symmetry of a Two-Particle Equation for Parastates

S.P. Onufriichuk, O.I. Prylypko

Pages: 385 - 387

We study hidden symmetry of a two-particle system of equations for parastates. Invariance operators are described for various potentials. It is a well-known fact that the systems of partial differential equations have a hidden symmetry, which can not be observed in the classical approach of Lie [1].

**Research Article**

## Lift of Invariant to Non-Invariant Solutions of Complex Monge-Ampère Equations

M.B. Sheftel, A.A. Malykh

Pages: 385 - 395

We show how partner symmetries of the elliptic and hyperbolic complex Monge-Ampère equations (CMA and HCMA) provide a lift of non-invariant solutions of three- and twodimensional reduced equations, i.e., a lift of invariant solutions of the original CMA and HCMA equations, to non-invariant solutions...

**Research Article**

## The Sylvester equation and integrable equations: I. The Korteweg-de Vries system and sine-Gordon equation

Dan-dan Xu, Da-jun Zhang, Song-lin Zhao

Pages: 382 - 406

The paper is to reveal the direct links between the well known Sylvester equation in matrix theory and some integrable systems. Using the Sylvester equation KM + MK = r sT we introduce a scalar function S(i, j) = sT Kj (I + M)−1Kir which is defined as same as in discrete case. S(i, j) satisfy some recurrence...

**Research Article**

## New extension of dispersionless Harry Dym hierarchy

Hongxia Wu, Jingxin Liu, Yunbo Zeng

Pages: 383 - 398

The symmetry constraint for dispersionless Harry Dym (dHD) hierarchy is derived for the first time by taking dispersionless limit of that for 2+1 dimensional Harry Dym hierarchy. Then, the dHD is extended by means of the symmetry constraint which we derived. From the zero-curvature equation of the new...

**Research Article**

## The Toy Top, an Integrable System of Rigid Body Dynamics

Boris A. Springborn

Pages: 387 - 410

A toy top is defined as a rotationally symmetric body moving in a constant gravittional field while one point on the symmetry axis is constrained to stay in a horizontal plane. It is an integrable system similar to the Lagrange top. Euler-Poisson equtions are derived. Following Felix Klein, the special...

**Short Communication**

## On Symmetry of the Generalized Breit Equation

S.P. Onufriichuk, O.I. Prylypko

Pages: 388 - 390

In this paper we find the complete set of symmetry operators for the two-particle Breit equation in the class of first-order differential operators with matrix coefficients. A new integral of motion is obtained.

**Research Article**

## A two-point boundary value problem on a Lorentz manifold arising in A. Poltorak's concept of reference frame

Peter S. Zykov, Yuri E. Gliklikh

Pages: 388 - 397

In A. Poltorak's concept, the reference frame in General Relativity is a certain manifold equipped with a connection. The question under consideration here is whether it is possible to join two events in the space-time by a time-like geodesic if they are joined by a geodesic of the reference frame connection...

**Research Article**

## The Scattering Approach for the Camassa—Holm equation

Jonatan Lenells

Pages: 389 - 393

We present an approach proving the integrability of the Camassa—Holm equation for initial data of small amplitude.

**Research Article**

## Integrability Conditions for Complex Homogeneous Kukles Systems

Jaume Giné, Claudia Valls

Pages: 387 - 398

In this paper we study the existence of local analytic first integrals for complex polynomial differential systems of the form ẋ = x + Pn(x, y), ẏ = −y, where Pn(x,y) is a homogeneous polynomial of degree n, called the complex homogeneous Kukles systems of degree n. We characterize all the homogeneous...

**Research Article**

## Nonlinear Maxwell Equations

G.A. Kotelnikov

Pages: 391 - 395

The infinite series of Lorentz and Poincaré-invariant nonlinear versions of the Maxwell equations are suggested. Some properties of these equations are considered.

**Research Article**

## Conformally Invariant Ansätze for the Maxwell Field

Victor Lahno

Pages: 392 - 400

A general procedure for construction of conformally invariant Ansätze for the Maxwell field is suggested. Ansätze invariant with respect to inequivalent three-parameter subgroups of the conformal group are constructed.

**Research Article**

## Similarity Reductions of the Zabolotskaya-Khokhlov Equation with a Dissipative Term

Masayoshi Tajiri

Pages: 392 - 397

Similarity reductions of the Zabolotskaya-Khokhlov equation with a dissipative term to one-dimensional partial differential equations including Burgers' equation are investigated by means of Lie's method of infinitesimal transformation. Some similarity solutions of the Z-K equation are obtained.

**Research Article**

## Riemann Invariants and Rank-k Solutions of Hyperbolic Systems

A.M. Grundland, B. Huard

Pages: 393 - 419

In this paper we employ a “direct method” to construct rank-k solutions, express- ible in Riemann invariants, to hyperbolic system of first order quasilinear differential equations in many dimensions. The most important feature of our approach is the analysis of group invariance properties of these solutions...

**Research Article**

## Two-component generalizations of the Novikov equation

Hongmin Li

Pages: 390 - 403

Some two-component generalizations of the Novikov equation, except the Geng-Xue equation, are presented, as well as their Lax pairs and bi-Hamiltonian structures. Furthermore, we study the Hamiltonians of the Geng-Xue equation and discuss the homogeneous and local properties of them.

**Research Article**

## On Einstein Equations on Manifolds and Supermanifolds

D. Leites, E. Poletaeva, V. Serganova

Pages: 394 - 425

The Einstein equations (EE) are certain conditions on the Riemann tensor on the real Minkowski space M. In the twistor picture, after complexification and compactifcation M becomes the Grassmannian Gr4 2 of 2-dimensional subspaces in the 4-dimesional complex one. Here we answer for which of the classical...

**Research Article**

## Laplace Invariants for General Hyperbolic Systems

Chris Athorne, Halis Yilmaz

Pages: 391 - 410

We consider the generalization of Laplace invariants to linear differential systems of arbitrary rank and dimension. We discuss completeness of certain subsets of invariants.

**Research Article**

## The Eigenvectors of the Heisenberg Hamiltonian with Elliptic Form of the Exchange Spin Interaction

V.I. Inozemtsev

Pages: 395 - 403

The eigenvectors of the Hamiltonian HN of N-site quantum spin chains with elliptic exchange are connected with the double Bloch meromorphic solutions of the quantum continuous elliptic Calogero-Moser problem. This fact allows one to find the eigenvetors via the solutions to the system of highly transcendental...

**Research Article**

## On Infinitesimal Symmetries of the Self-Dual Yang-Mills Equations

T.A. Ivanova

Pages: 396 - 404

Infinite-dimensional algebra of all infinitesimal transformations of solutions of the self-dual Yang-Mills equations is described. It contains as subalgebras the infinitedimensional algebras of hidden symmetries related to gauge and conformal transformations.

**Research Article**

## *-Representations of the Quantum Algebra Uq(sl(3))

L.B. Turovskaya

Pages: 396 - 401

Studied in this paper are real forms of the quantum algebra Uq(sl(3)). Integrable operator representations of *-algebras are defined. Irreducible representations are classified up to a unitary equivalence.

**Research Article**

## The Point of Maximum Curvature as a Marker for Physiological Time Series

James Robert Stirling, Maria Zakynthinaki

Pages: 396 - 406

We present a geometric analysis of the model of Stirling et al. [14]. In particular we analyze the curvature of a heart rate time series in response to a step like increment in the exercise intensity. We present solutions for the point of maximum curvature which can be used as a marker of physiological...

**Research Article**

## Integrable Boundary Conditions for the Hirota-Miwa Equation and Lie Algebras

Ismagil Habibullin, Aigul Khakimova

Pages: 393 - 413

Systems of discrete equations on a quadrilateral graph related to the series DN(2) of the affine Lie algebras are studied. The systems are derived from the Hirota-Miwa equation by imposing boundary conditions compatible with the integrability property. The Lax pairs for the systems are presented. It...

**Research Article**

## Proper rational and analytic first integrals for asymmetric 3-dimensional Lotka-Volterra systems

Jaume Llibre, Clàudia Valls

Pages: 393 - 404

We go beyond in the study of the integrability of the classical model of competition between three species studied by May and Leonard [19], by considering a more realistic asymmetric model. Our results show that there are no global analytic first integrals and we provide all proper rational first integrals...

**Research Article**

## Bayesian Approach to the Determination of the Kinetic Parameters of DNA Hairpins Under Tension

Marco Ribezzi-Crivellari, Mario Wagner, Felix Ritort

Pages: 397 - 410

In this paper we propose a Bayesian scheme for the determination of the unfolding and refolding kinetic rates of DNA hairpins under tension. This method is based on the hypothesis that the unfolding-refolding dynamics is well described by a Markov Chain. The results from the Bayesian method are contrasted...

**Research Article**

## Darboux integrability of a generalized Friedmann-Robertson-Walker Hamiltonian system

Jaume Llibre, Claudia Valls

Pages: 394 - 406

We study the Darboux first integrals of a generalized Friedmann-Robertson-Walker Hamiltonian system.

**Research Article**

## The Bäcklund and the Galilei Invariant Transformations Constructed by Similarity Variables for Soliton Equations

Shunji Kawamoto

Pages: 398 - 404

The Painlevé-test has been applied to checking the integrability of nonlinear PDEs, since similarity solutions of many soliton equations satisfy the Painlevé equation. As is well known, such similarity solutions can be obtained by the infinitesimal transformation, that is, the classical similarity analysis,...

**Research Article**

## Euler-Poincaré Formalism of (Two Component) Degasperis-Procesi and Holm-Staley type Systems

Partha Guha

Pages: 398 - 429

In this paper we propose an Euler-Poincaré formalism of the Degasperis and Procesi (DP) equation. This is a second member of a one-parameter family of partial dif- ferential equations, known as b-field equations. This one-parameter family of pdes includes the integrable Camassa-Holm equation as a first...

**Research Article**

## Doubly periodic waves of a discrete nonlinear Schrodinger system with saturable nonlinearity

Robert Conte, K. W. Chow

Pages: 398 - 409

A system of two discrete nonlinear Schr¨odinger equations of the Ablowitz-Ladik type with a saturable nonlinearity is shown to admit a doubly periodic wave, whose long wave limit is also derived. As a by-product, several new solutions of the elliptic type are provided for NLS-type discrete and continuous...

**Research Article**

## Algebro-geometric Constructions of Quasi Periodic Flows of the Discrete Self-dual Network Hierarchy and Applications

Dong Gong, Xianguo Geng

Pages: 395 - 427

In this paper we obtain the discrete integrable self-dual network hierarchy associated with a discrete spectral problem. On the basis of the theory of algebraic curves, the continuous flow and discrete flow related to the discrete self-dual network hierarchy are straightened using the Abel-Jacobi coordinates....

**Research Article**

## Sundman Symmetries of Nonlinear Second-Order and Third-Order Ordinary Differential Equations

Norbert Euler, Marianna Euler

Pages: 399 - 421

We investigate the Sundman symmetries of second-order and third-order nonlinear odinary differential equations. These symmetries, which are in general nonlocal tranformations, arise from generalised Sundman transformations of autonomous equations. We show that these transformations and symmetries can...

**Research Article**

## Two New Solvable Dynamical Systems of Goldfish Type

F. Calogero

Pages: 397 - 414

Two new solvable dynamical systems of goldfish type are identified, as well as their isochronous variants. The equilibrium configurations of these isochronous variants are simply related to the zeros of appropriate Laguerre and Jacobi polynomials.

**Research Article**

## On Radial Schrödinger Equations in Curved Spaces and Their Spectra Through Nonlinear Constraints

J. Beckers, N. Debergh

Pages: 401 - 408

First, we determine the radial Schrödinger equation in D-dimensional curved spaces when central problems are considered. Second, we develop the so-called factorization method on the basis of supersymmetric arguments for solving such radial equations when D = 1, 2, 3-harmonic oscillator and D = 3-hydrogen...

**Research Article**

## Eigenvectors of the recursion operator and a symmetry structure for the coupled KdV hierarchy

Sen-Yue Lou

Pages: 401 - 413

It is shown that eigenvectors of the recursion operator L with the eigenvalue i and the inverse of the recursion operator Li L-i for the coupled KdV hierarchy (CKdVH) can be obtained in terms of squared eigenfunctions of the associated linear problem. The symmetry structure and corresponding infinite...

**Research Article**

## Three-Generation Distler-Kachru Models

Yu.I. Samoilenko, Yu.M. Malyuta, N.N. Aksenov

Pages: 402 - 408

**Research Article**

## The description of reflection coefficients of the scattering problems for finding solutions of the Korteweg–de Vries equations

Pham Loi Vu

Pages: 399 - 432

The results of inverse scattering problem associated with the initial-boundary value problem (IBVP) for the Korteweg–de Vries (KdV) equation with dominant surface tension are formulated. The necessary and sufficient conditions for given functions to be the left- and right-reflection coefficients of the...

**Research Article**

## Explicit solutions for a nonlinear model on the honeycomb and triangular lattices

V.E. Vekslerchik

Pages: 399 - 422

We study a simple nonlinear model deﬁned on the honeycomb and triangular lattices. We propose a bilin-earization scheme for the ﬁeld equations and demonstrate that the resulting system is closely related to the well-studied integrable models, such as the Hirota bilinear difference equation and the Ablowitz-Ladik...

**Research Article**

## Canonically Transformed Detectors Applied to the Classical Inverse Scattering Problem

C. Jung, T.H. Seligman, J.M. Torres

Pages: 404 - 411

The concept of measurement in classical scattering is interpreted as an overlap of a particle packet with some area in phase space that describes the detector. Considering that usually we record the passage of particles at some point in space, a common detector is described e.g. for one-dimensional systems...

**Research Article**

## How to Find Discrete Contact Symmetries

Peter E. Hydon

Pages: 405 - 416

This paper describes a new algorithm for determining all discrete contact symmetries of any differential equation whose Lie contact symmetries are known. The method is constructive and is easy to use. It is based upon the observation that the adjoint action of any contact symmetry is an automorphism...

**Research Article**

## Non-Lie Symmetries and Supersymmetries

Anatolii Nikitin

Pages: 405 - 415

Appeared more than one century ago, the classical Lie approach serves as a powerful tool in investigations of symmetries of partial differential equations. In the last three decades there appear essential generalizations of this approach. They are the modern version of the Lie-Bäcklund symmetries [1],...

**Research Article**

## Semidiscrete Integrable Nonlinear Systems Generated by the New Fourth-Order Spectral Operator: Local Conservation Laws

Oleksiy O. Vakhnenko

Pages: 401 - 414

Starting with the semidiscrete integrable nonlinear Schrödinger system on a zigzag-runged ladder lattice we have presented the generalization and an essentially off-diagonal enlargement of its spectral operator which in the framework of zero-curvature equation allows to generate at least two new types...

**Research Article**

## On the Origin of Fractional Shapiro Steps in Systems of Josephson Junctions with Few Degrees of Freedom

A. Valizadeh, M.R. Kolahchi, J.P. Straley

Pages: 407 - 416

We investigate the origin of fractional Shapiro steps in arrays consisting of a few overdamped Josephson junctions. We show that when the symmetry reduces the equations to that of a single junction equation, only integer steps appear. Otherwise, fractional steps will appear when the evolution equations...

**Research Article**

## Bilinear Identities and Squared Eigenfunction Symmetries of the *BC*_{r}-KP Hierarchy

_{r}

Lumin Geng, Huizhan Chen, Na Li, Jipeng Cheng

Pages: 404 - 419

The BCr-KP hierarchy is an important sub hierarchy of the KP hierarchy, which includes the BKP and CKP hierarchies as the special cases. Some properties of the BCr-KP hierarchy and its constrained case are investigated in this paper, including bilinear identities and squared eigenfunction symmetries....

**Research Article**

## Functional Representation of the Volterra Hierarchy

V.E Vekslerchik

Pages: 409 - 431

In this paper I study the functional representation of the Volterra hierarchy (VH). Using the Miwa's shifts I rewrite the infinite set of Volterra equations as one functional equation. This result is used to derive a formal solution of the associated linear problem, a generating function for the conservation...

**Research Article**

## On Classification of Subalgebras of the Poincaré Algebra

Leonid F. Barannyk

Pages: 409 - 417

The substantiation of the algorithm for classifying subalgebras of the Poincaré algebra AP(1, n) up to P(1, n)-conjugacy is completed

**Research Article**

## Nonlocal Symmetry of Nonlinear Wave Equations

V.A. Tychynin

Pages: 409 - 413

A class of nonlinear wave equations is considered. Symmetry of these equations is extended using nonlocal transformations.

**Research Article**

## Ideals generated by traces or by supertraces in the symplectic reflection algebra *H*_{1,ν} (*I*_{2}(2*m* + 1))

S.E. Konstein, I.V. Tyutin

Pages: 405 - 425

For each complex number ν, an associative symplectic reflection algebra ℋ := H1,ν (I2(2m + 1)), based on the group generated by root system I2(2m + 1), has an m-dimensional space of traces and an (m + 1)-dimensional space of supertraces. A (super)trace sp is said to be degenerate if the corresponding...

**Research Article**

## Asymptotically isochronous systems

Francesco Calogero, David Gomez-Ullate

Pages: 410 - 426

Mechanisms are elucidated underlying the existence of dynamical systems whose generic solutions approach asymptotically (at large time) isochronous evolutions: all their dependent variables tend asymptotically to functions periodic with the same fixed period. We focus on two such mechanisms, emphasizing...

**Research Article**

## Dromion Perturbation for the Davey-Stewartson-1 Equations

O.M. Kiselev

Pages: 411 - 422

The perturbation of the dromion of the Davey-Stewartson-1 equation is studied over the large time.

**Research Article**

## r-Matrices for Relativistic Deformations of Integrable Systems

Yuri B. Suris

Pages: 411 - 447

We include the relativistic lattice KP hierarchy, introduced by Gibbons and Kupershmidt, into the r-matrix framework. An r-matrix account of the nonrelativistic lattice KP hierarchy is also provided for the reader's convenience. All relativistic constructions are regular one-parameter perturbations of...

**Research Article**

## Phenomenological Modeling of DNA Overstretching

Ray W. Ogden, Giuseppe Saccomandi, Ivonne Sgura

Pages: 411 - 427

A phenomenological model based on the three-dimensional theory of nonlinear elasticity is developed to describe the phenomenon of overstretching in the force-extension curve for double-stranded DNA (dsDNA). By using the concept of a material with multiple reference configurations a single formula is...

**Research Article**

## Dark Equations and Their Light Integrability

Denis Blackmore, Anatolij K. Prykarpatski

Pages: 407 - 428

A relatively new approach to analyzing integrability, based upon differential-algebraic and symplectic techniques, is applied to some “dark equations ”of the type introduced by Boris Kupershmidt. These dark equations have unusual properties and are not particularly well-understood. In particular, dark...

**Research Article**

## Rogue wave management in an inhomogeneous Nonlinear Fibre with higher order effects

J.S. He, Y.S. Tao, K. Porsezian, A.S. Fokas

Pages: 407 - 419

We consider an inhomogeneous Hirota equation with variable dispersion and nonlinearity. We introduce a novel transformation which maps this equation to a constant coefficient Hirota equation. By employing this transformation we construct the rogue wave solution of the inhomogeneous Hirota equation. Furthermore,...