On the Tau Function for the Schlesinger Equation of Isomonodromic Deformations

The tau function for the Schlesinger equation of isomonodromic deformations is represented as the result of successively applied elementary gauge transformations; this, in particular, suggests a simple proof for the Miwa theorem about the tau function.     

Symmetries of the Four-Matrix Schlesinger System

All types of symmetries for the Schlesinger system are considered. A new form of the Schlesinger system and the action of the modular group on the corresponding linear system are studied. The geometric meaning of the Okamoto transformation is discussed. Bibliography: 11 titles.     

非线性发展方程的Jacobi椭圆函数解

借助齐次平衡原则,提出了一种新的构造非线性发展方程的Jacobi椭圆函数精确解的方法. 并利用之得到了KdV方程,Boussinesq方程,KGS方程组的新形式 Jacobi椭圆函数解.     

非线性发展方程的Jacobi椭圆函数解

借助齐次平衡原则,提出了一种新的构造非线性发展方程的Jacobi椭圆函数精确解的方法.并利用之得到了KdV方程,Boussinesq方程,KGS方程组的新形式Jacobi椭圆函数解.     

New Jacobi Elliptic Function Solutions for the Generalized Nizhnik-Novikov-Veselov Equation

In this paper,a new generalized Jacobi elliptic function expansion method based upon four new Jacobi elliptic functions is described and abundant solutions of new Jacobi elliptic functions for the gene...     

求解函数解析式的解方程组法

针对函数方程f(x)+bf(g(x))=h(x),其中f(x)为待求函数,b为任意实数,h(x)为已知函数,g(x)满足gn(x)=x.经过多次迭代换元,构建由待求函数构成的线性方程组,运用Cramer法则,可得出该函数方程有唯一解的充要条件为bn≠(-1)n,且此时可解出f(x)=1/1-(1-b)nn-1Σi=0(-b)ih(gi(x)).     

Residue Theorem and Theta Function Identities

In this paper we will use the residue theorem of elliptic functions to prove some theta function identities of Ramanujan. We also derive some new identities by this method.     

广义Pochhammer-Chree方程的新孤波解和余弦周期波解

本文利用假设待定法求出了具5阶非线性项的广义Pochhammer-Chree方程具双曲正割函数分式形式的2个新孤波解和6个余弦函数周期波解,并分别给出了它们的有界性条件.揭示了行波波速v的改变与钟状孤波解和余弦周期波解波形变化的相关性.     

A New Evans Function for Quasi-Periodic Solutions of the Linearised Sine-Gordon Equation

We construct a new Evans function for quasi-periodic solutions to the linearisation of the sine-Gordon equation about a periodic travelling wave. This Evans function is written in terms of fundamental solutions to a Hill’s equation. Applying the Evans-Krein function theory of Kollár and Miller (SIAM Rev 56(1):73–123, 2014) to our Evans function, we provide a new method for computing the Krein signatures of simple characteristic values of the linearised sine-Gordon equation. By varying the Floquet exponent parametrising the quasi-periodic solutions, we compute the linearised spectra of periodic travelling wave solutions of the sine-Gordon equation and track dynamical Hamiltonian–Hopf bifurcations via the Krein signature. Finally, we show that our new Evans function can be readily applied to the general case of the nonlinear Klein–Gordon equation with a non-periodic potential.

     

Jacobi Elliptic Function Solutions and Traveling Wave Solutions of the (2 + 1)-Dimensional Gardner-KP Equation

The fully integrable KP equation is one of the models that describes the evolution of nonlinear waves, the expansion of the well-known KdV equation, where the impacts of surface tension and viscosity are negligible. This paper uses the Modified Extended Direct Algebraic (MEDA) method to build fresh exact, periodic, trigonometric, hyperbolic, rational, triangular and soliton alternatives for the (2 + 1)-dimensional Gardner KP equation. These solutions that we discover in this article will help us understand the phenomena of the (2 + 1)-dimensional Gardner KP equation. Comparing the study in this paper and existing work, we find more exact solutions with soliton and periodic structures and the rational function solution in this paper is more general than the rational solution in existing literature. Most of the Jacobi elliptic function solutions and the mixed Jacobi elliptic function solutions to the (2 + 1)-dimensional Gardner KP equation discovered in this paper, to the best of our highest understanding are not seen in any existing paper until now.     

Complete Families of Solutions for the Dirac Equation Using Bicomplex Function Theory and Transmutations

The Dirac equation with a scalar and an electromagnetic potential is considered. In the time-harmonic case and when all the involved functions depend only on two spatial variables it reduces to a pair of decoupled bicomplex Vekua-type equations [8]. Using the technique developed for complex Vekua equations a system of exact solutions for the bicomplex equation is constructed under additional conditions, in particular when the electromagnetic potential is absent and the scalar potential is a function of one Cartesian variable. Introducing a transmutation operator relating the involved bicomplex Vekua equation with the Cauchy-Riemann equation we prove the expansion and the Runge approximation theorems corresponding to the constructed family of solutions.     

与Smarandache函数有关的一个方程的解的注记

设φ(n)、S(n)分别表示正整数n的Euler函数和Smarandache函数,白海荣和廖群英在[Smarandache函数的几类相关方程的解,数学学报中文版,2019,62(2):247-254]中称方程φ(n)=∑d|nS(d)只有两个解,分别为n=2^5和n=3×2^5.本文指出,这两个数均不是此方程的解,并指出其出错原因是因为他们对M?bius反转公式的错误理解所造成的.     

Isomonodromy Approach to Boundary Value Problems for the Ernst Equation

We use the isomonodromy properties of theta-functional solutions of the Ernst equation and an asymptotic expansion in the spectral parameter to establish algebraic relations, enforced by the underlying Riemann surface, between the metric functions and their derivatives. These relations determine which classes of boundary value problems can be solved on a given surface. The situation on lower-genus Riemann surfaces is studied in detail.     

五阶变系数模型方程新的Jacobi椭圆函数解

我们给出了一种统一的Jacobi椭圆函数方法来构造非线性偏微分方程精确行波解的新方法．借助于Mathematica，我们获得了五阶变系数模型方程的24种Jacobi椭圆函数解．     

A Finite Group Related to the Cubic Theta Function

With the Kubota-Patterson cubic theta function 27 shifted theta functions are associated. Then a certain group of permutations of the shifted theta functions is defined in a natural way, which proves to be isometric to a subgroup of the known group of permutations of 27 lines on a cubic surface. Bibliography: 17 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 314, 2004, pp. 196–212.     

一个Bargmann系统及一类演化方程解的对合表示

本文通过一个特征值问题的非线性化,得到了一个Bargmann系统并证明了它是Liouville意义下的完全可积系统,并给出了与这个特征值问题相联系的演化方程解的对合表示。     

On the Solutions of an Equation Involving the Smarandache Power Function SP（n）

For any positive integer n,the famous Smarandache power function SP(n) is defined as the smallest positive integer m such that n|mm,where m and n have the same prime divisors.The main purpose of this paper is using the elementary methods to study the positive integer solutions of an equation involving the Smarandache power function SP(n) and obtain some interesting results.At the same time,we give an open problem about the related equation.     

Elliptic Families of Solutions of the Kadomtsev--Petviashvili Equation and the Field Elliptic Calogero--Moser System

We present a Lax pair for the field elliptic Calogero-Moser system and establish a connection between this system and the Kadomtsev-Petviashvili equation. Namely, we consider elliptic families of solutions of the KP equation such that their poles satisfy a constraint of being balanced. We show that the dynamics of these poles is described by a reduction of the field elliptic CM system.We construct a wide class of solutions to the field elliptic CM system by showing that any N-fold branched cover of an elliptic curve gives rise to an elliptic family of solutions of the KP equation with balanced poles.     

Theta Series of Quaternion Algebras over Function Fields

Let K be the function field over a finite field of odd order, and let H be a definite quaternion algebra over K. If Λ is an order of level M in H, we define theta series for each ideal I of Λ using the reduced norm on H. Using harmonic analysis on the completed algebra H_∞ and the arithmetic of quaternion algebras, we establish a transformation law for these theta series. We also define analogs of the classical Hecke operators and show that in general, the Hecke operators map the theta series to a linear combination of theta series attached to different ideals, a generalization of the classical Eichler Commutation Relation.