一个新的非等谱可积族和一些相关对称

利用李群$M_nC$的一个子群我们引入一个线性非等谱问题,该问题的相容性条件可导出演化方程的一个非等谱可积族,该可积族可约化成一个广义非等谱可积族.这个广义非等谱可积族可进一步约化成在物理学中具有重要应用的标准非线性薛定谔方程和KdV方程.基于此,我们讨论在广义非等谱可积族等谱条件下的一个广义AKNS族$u_t=K_m(u)$的$K$对称和$\tau$对称.此外,我们还考虑非等谱AKNS族$u_t=\tau_{N+1}^l$的$K$对称和$\tau$对称.最后,我们得到这两个可积族的对称李代数,并给出这些对称和李代数的一些应用,即生成了一些变换李群和约化方程的无穷小算子.     

耦合KdV方程及无穷守恒律

通过一个带有4个位势的3×3矩阵谱问题,借助于零曲率方程,得到一族非线性演化方程.通过适当的约化,构造出了耦合KdV方程,并且给出了它的无穷守恒律.     

一族包含任意多个未知函数的可积方程组

基于 Lie代数 A1,建立了一个等谱问题 ,由相应的零曲率方程 ,导出一族可积方程组 ,其中未知函数个数可以是任意的     

与含有三个位势矩阵谱问题相联系的非线性发展方程族及其Hamilton结构

从含有三个位势的4×4矩阵谱问题出发,导出两类非线性发展方程.然后利用迹公式,给出了这两类方程的广义Hamilton结构.     

AKNS方程族新的可积耦合

在本文中,通过对一个新的广义AKNS谱问题的研究,得到AKNS方程族新的广义可积耦合方程族,其中等谱形式与非等谱形式分别得到讨论,给出相应的哈密顿系统.     

两个可积系统及其约化

该文引入了一个李代数,然后定义了其相应的两个圈代数,利用圈代数构造了两个等谱问题,其相容性条件导出了两个可积动力系统.通过约化这样的系统,得到了某些有趣的非线性方程,如Burgers方程、组合KdV-MKdV方程和Kuramoto-Sivashinsky方程以及KdV方程的一种推广形式.最后,利用贝尔多项式讨论了广义KdV方程的可积性质,包括双线性形式、Lax对、贝克隆变换和无穷守恒律等.     

广义KN方程族及其Hamilton结构

构造了一个带有任意光滑函数的等谱问题,利用屠规彰格式得到广义KN 方程族及其Hamilton结构,并且当f=0时,变为著名的KN谱,当f=-12qr时,变为Qiao谱.     

广义耦合KdV孤子方程的达布变换及其奇孤子解

借助谱问题的规范变换,给出广义耦合KdV孤子方程的达布变换,利用达布变换来产生广义耦合KdV孤子方程的奇孤子解,并且用行列式的形式来表达广义耦合KdV孤子方程的奇孤子解.作为应用,广义耦合KdV孤子方程奇孤子解的前两个例子被给出.     

广义的带导数非线性薛定谔方程的有理解

广义带导数非线性薛定谔方程是与Kaup-Newell谱问题相联系的一个非线性发展方程,方程可在合适的条件方程下,利用Wronsiki技巧,寻找广义双Wronsikian形式的一般解,进而得到其孤子解和有理解.     

基于李代数sl(m+1,R)的多分量扰动AKNS孤子梯队

基于李代数sl(m+1,R),提出了一个新的多分量矩阵谱问题,进而利用零曲率公式构造了新的多分量扰动AKNS孤子梯队.利用迹恒等式构造了双哈密顿结构,同时给出了遗传递推算子.     

The two generalized AKNS hierarchies and their Hamiltonian structures

With the help of the known Lie algebra G₁ and a new Lie algebra G₂, the two different isospectral problem are designed. Making use of the zero curvature equation and the tri-trace identity, the two generalized AKNS hierarchies and their Hamiltonian structures are obtained, respectively.     

Three nonlinear integrable couplings of the nonlinear Schrödinger equations

Based on two types of expanding Lie algebras of a Lie algebra G, three isospectral problems are designed. Under the framework of zero curvature equation, three nonlinear integrable couplings of the nonlinear Schröding equations are generated. With the help of variational identity, we get the Hamiltonian structure of one of them. Furthermore, we get the result that the hierarchy is also integrable in sense of Liouville.     

Symmetries for the Ablowitz–Ladik Hierarchy: Part I. Four‐Potential Case

In the paper, we first investigate symmetries of isospectral and non‐isospectral four‐potential Ablowitz–Ladik hierarchies. We express these hierarchies in the form of u_n,t= L^mH⁽⁰⁾ , where m is an arbitrary integer (instead of a nature number) and L is the recursion operator. Then by means of the zero‐curvature representations of the isospectral and non‐isospectral flows, we construct symmetries for the isospectral equation hierarchy as well as non‐isospectral equation hierarchy, respectively. The symmetries, respectively, form two centerless Kac‐Moody‐Virasoro algebras. The recursion operator L is proved to be hereditary and a strong symmetry for this isospectral equation hierarchy. Besides, we make clear for the relation between four‐potential and two‐potential Ablowitz–Ladik hierarchies. The even order members in the four‐potential Ablowitz–Ladik hierarchies together with their symmetries and algebraic structures can be reduced to two‐potential case. The reduction keeps invariant for the algebraic structures and the recursion operator for two potential case becomes L² .     

The hierarchy of an integrable coupling and its Hamiltonian structure

A type of higher dimensional loop algebra is constructed from which an isospectral problem is established. It follows that an integrable coupling, actually an extended integrable model of the existed solitary hierarchy of equations, is obtained by taking use of the zero curvature equation, whose Hamiltonian structure is worked out by employing the constructed quadratic identity.     

Two expanding integrable systems and quasi-Hamiltonian function associated with an equation hierarchy

A Lie algebra sl(2) which is isomorphic to the known Lie algebra A₁ is introduced for which an isospectral Lax pair is presented, whose compatibility condition leads to a soliton-equation hierarchy. By using the trace identity, its Hamiltonian structure is obtained. Especially, as its reduction cases, a Sine equation and a complex modified KdV(cmKdV) equation are obtained,respectively. Then we enlarge the sl(2) into a bigger Lie algebra sl(4) so that a type of expanding integrable model of the hierarchy is worked out. However, the soliton-equation hierarchy is not integrable couplings. In order to generate the integrable couplings, an isospectral Lax pair is introduced. Under the frame of the zero curvature equation, we generate an integrable coupling whose quasi-Hamiltonian function is derived by employing the variational identity. Finally, two types of computing formulas of the constant γ are obtained, respectively.     

Integrable couplings and Hamiltonian structures of the L-hierarchy and the T-hierarchy

An algebraic system is constructed from which establishes two isospectral problems. By solving the zero curvature equations, two resulting integrable couplings of the Li hierarchy and Tu hierarchy are obtained, respectively. By making use of the quadratic-form identity, the Hamiltonian structures of the above integrable couplings are generated, which are Liouville integrable.     

Generalized nonisospectral super integrable hierarchies

For the Lie superalgebra B(0,1), we choose a set of basis matrices. Then we consider a linear combination of the basis matrices, which is exactly the spectral matrix of the spatial part for the super Ablowitz‐Kaup‐Newell‐Segur (AKNS) hierarchy. The compatible condition of the spatial and temporal spectral problems leads to the well‐known zero curvature equation. Here, when the spectral parameter is independent (dependent) of temporal parameter, we obtain isospectral (nonisospectral) super AKNS hierarchy. Furthermore, we derive the generalized nonisospectral super AKNS hierarchy (GNI‐SAKNS). As another example, similar method is successfully applied to the super Dirac hierarchy, and we obtain the generalized nonisospectral super Dirac hierarchy (GNI‐SD).     

Two types of Lie super-algebra for the super-integrable Tu-hierarchy and its super-Hamiltonian structure

Two different Lie super-algebras are constructed which establish two isospectral problems. Under the frame of the zero curvature equations, the corresponding super-integrable hierarchies of the Tu-hierarchy are obtained. By making use of the super-trace identity, the super-Hamiltonian structures of the above integrable hierarchies are generated, which are Liouville integrable.