对称群S5的表示环

本文利用有限群特征标理论计算了对称群S₅的所有不可约复表示的幂公式.根据求解幂公式过程中得到的S₅任意两个不可约表示张量积的分解情况,作者刻画了S₅上表示环r(S₅)及其若干结构性质,如极小生成元关系式表达、单位群、本原幂等元、行列式与Casimir数.     

KdV方程的延拓结构

利用外微分形式系统和Lie代数表示理论提出了求解非线性波方程Lax对的延拓结构理论,该方法是构造非线性波方程Lax对的系统最有效的方法.其关键在于如何给出延拓代数的具体表示,如微分算子表示或矩阵表示.如果一个非线性波方程具有非平凡的延拓代数,则称其延拓代数可积,本篇论文主要利用延拓结构理论,讨论KdV方程的解,同时给出...     

刚性Volterra泛函微分方程梯形方法的B-理论

最近,李寿佛建立了刚性Volterra泛函微分方程Runge_Kutta方法和一般线性方法的B-理论,其中代数稳定是数值方法B-稳定与B-收敛的首要条件,但梯形方法表示成Runge—Kutta方法的形式或一般线性方法的形式都不是代数稳定的,因此上述理论不适用于梯形方法.本文从另一途径出发,证明求解刚性Volterra泛函微分方程的梯形方法是B-稳定且2阶最佳B-收敛的,最后的数值试验验证了所获理论的正确性.     

第二类Volterra型积分方程的Chebyshev-Legendre谱配置方法

提出了一种新的求解第二类线性Volterra型积分方程的Chebyshev谱配置方法.该方法分别对方程中积分部分的核函数和未知函数在Chebyshev-Gauss-Lobatto点上进行插值,通过Chebyshev-Legendre变换,把插值多项式表示成Legendre级数形式,从而将积分转换为内积的形式,再利用Legendre多项式的正交性进行计算.利用Chebyshev插值算子在不带权范数意义下的逼近结果,对该方法在理论上给出了L∞范数意义下的误差估计,并通过数值算例验证了算法的有效性和理论分析的正确性.     

Kazhdan-Lusztig理论:起源、发展、影响和一些待解决的问题

Kazhdan-Lusztig理论是代数群表示论近40年来最重要的发展之一.该理论在很多重要问题的解决上起关键作用,如有限Lie型群的不可约特征标的分类和Lie理论中某些不可约表示的特征标的确定等.同时该理论开创了很多有活力的研究课题,如Kazhdan-Lusztig多项式的研究、Coxeter群的胞腔的研究及Coxeter群与相交上同调和K理论的联系等.本文将简要介绍这一理论的起源、发展、影响和一些未解决的问题.     

求收益模糊的贝叶斯纳什均衡解的结构元方法

主要目的是利用结构元方法求解收益模糊的贝叶斯纳什均衡.首先,在原有结构元理论基础上,给出了多元模糊值函数的定义及其结构元表示;其次,给出了在混合策略下,收益模糊的贝叶斯纳什均衡的定义,并证明了其存在性定理;然后,利用结构元理论,将该博弈模型等价地转化为一个经典的博弈模型,简化了原问题的求解.最后的应用实例说明了该方法的有效性.     

利用F-展开法求解ZK-BBM方程

利用F-展开法求解出了ZK-BBM方程的双周期波解,并在极限形式下得到了ZK-BBM方程的孤波解和单周期波解.从而丰富了该方程解的理论.此方法也可适用求解其它非线性发展方程.     

四元Heisenberg群上次拉普拉斯算子的m幂次的基本解

本文研究了四元Heisenberg群上次拉普拉斯算子的m幂次的基本解,该结论是Heisenberg群上结果的推广.本文利用了四元Heisenberg群上的Fourier变换理论构造了该群上次拉普拉斯算子的m幂次的基本解,并且给出了基本解的积分表示.     

关于体上分块矩阵的群逆

本文利用分块矩阵方法．研究了体上两个矩阵乘积的群逆的存在性及表示形式，给出了体上两个矩阵乘积群逆存在的充分必要条件和表示形式．并且在一定条件下．给出了体上分块矩阵的群逆存在性及表示形式．     

动力学群微分表示的计算:以Lorentz群 SO(3,1) 为例

该文给出了动力学群在群参数空间以及陪集空间上的右、左微分表示和伴随微分表示的符号计算方法.作为例子, 计算了Lorentz 群SO(3,1)的6 -参数和3 -参数的右、左及伴随微分表示,这些表示是旋转群SO(3)关于欧拉角和极角的微分表示的相对论性推广.特别,作者给出了伴随微分表示的两种不同的3 -参数形式,同时也得到了Wigner小群SO(2,1) 和 SO(3)$的6 -参数和3 -参数的相应表示.这些表示在相对论性量子陀螺的研究中可得到应用.     

An operational calculus for the euclidean motion group with applications in robotics and polymer science

In this article we develop analytical and computational tools arising from harmonic analysis on the motion group of three-dimensional Euclidean space. We demonstrate these tools in the context of applications in robotics and polymer science. To this end, we review the theory of unitary representations of the motion group of three dimensional Euclidean space. The matrix elements of the irreducible unitary representations are calculated and the Fourier transform of functions on the motion group is defined. New symmetry and operational properties of the Fourier transform are derived. A technique for the solution of convolution equations arising in robotics is presented and the corresponding regularized problem is solved explicity for particular functions. A partial differential equation from polymer science is shown to be solvable using the operational properties of the Euclidean-group Fourier transform.     

A Hermitian Cauchy formula on a domain with fractal boundary

Euclidean Clifford analysis is a higher dimensional function theory offering a refinement of classical harmonic analysis. The theory is centered around the concept of monogenic functions, i.e. null solutions of a first order vector valued rotation invariant differential operator called Dirac operator, which factorizes the Laplacian; monogenic functions may thus also be seen as a generalization of holomorphic functions in the complex plane. Hermitian Clifford analysis offers yet a refinement of the Euclidean case; it focusses on the simultaneous null solutions, called Hermitian (or h-) monogenic functions, of two Hermitian Dirac operators which are invariant under the action of the unitary group. In Brackx et al. (2009) [8] a Clifford-Cauchy integral representation formula for h-monogenic functions has been established in the case of domains with smooth boundary, however the approach followed cannot be extended to the case where the boundary of the considered domain is fractal. At present, we investigate an alternative approach which will enable us to define in this case a Hermitian Cauchy integral over a fractal closed surface, leading to several types of integral representation formulae, including the Cauchy and Borel-Pompeiu representations.     

Coercive estimates and integral representation formulas on carnot groups

We establish Sobolev-type integral representation formulas for differential functions on Carnot groups. We prove coercive estimates for homogeneous differential operators with constant coefficients and finite-dimensional kernel. These integral representation formulas are new in the Euclidean spaces as well.     

Surfaces of revolution in the Heisenberg group and the spectral generalization of the Willmore functional

We study the generalization of the Willmore functional for surfaces in the three-dimensional Heisenberg group. Its construction is based on the spectral theory of the Dirac operator entering into theWeierstrass representation of surfaces in this group. Using the surfaces of revolution we demonstrate that the generalization resembles the Willmore functional for the surfaces in the Euclidean space in many geometrical aspects. We also observe the relation of these functionals to the isoperimetric problem.     

Martin Integral Representation for Nonharmonic Functions and Discrete Co-Pizzetti Series

In this paper, we study the Martin integral representation for nonharmonic functions in discrete settings of infinite homogeneous trees. Recall that the Martin integral representation for trees is analogs to the mean-value property in Euclidean spaces. In the Euclidean case, the mean-value property for nonharmonic functions is provided by the Pizzetti (and co-Pizzetti) series. We extend the co-Pizzetti series to the discrete case. This provides us with an explicit expression for the discrete mean-value property for nonharmonic functions in discrete settings of infinite homogeneous trees.

     

Integral Formula of Isotonic Functions over Unbounded Domain in Clifford Analysis

In this paper we mainly study the so-called isotonic Dirac system over more general types of unbounded domains in Euclidean space of even dimension. In such systems different Dirac operators in the half dimension act from the left and from the right on the functions considered. We obtain the integral representation of isotonic functions satisfying the decay condition over the unbounded domains, and show that the integral representation formula over the unbounded domains for holomorphic functions of several complex variables and for Hermitean monogenic functions may be derived from it.     

Characterization of Multidimensional Euclidean Landau States by Coherent State Transformations

We deal with a family of multidimensional generalized coherent states obtained using the Fock–Bargmann representation of the Heisenberg group. We prove that the ranges of the corresponding coherent state transformations coincide with the spaces of bound states of an even-dimensional analogue of a charged particle in a uniform magnetic field. This provides a new characterization of Euclidean Landau states.     

Matrix Groups Related to the Quaternion Group and Spherical Orbit Codes

We consider a finite matrix group with 3⁴· 2¹⁶ elements, which is a subgroup of the infinite group , where is the regular representation of the quaternion group and C is a matrix that transforms the regular representation Q to its cellwise-diagonal form. There is a number of ways to define the matrix C. Our aim is to make the group similar in a certain sense to a finite group. The eventual choice of an appropriate matrix C done heuristically. We study the structure of the group and use this group to construct spherical orbit codes on the unit Euclidean sphere in R⁸. These codes have code distance less than 1. One of them has 3²· 2⁸ = 2304 elements and its squared Euclidean code distance is 0.293. Communicated by: V. A. Zinoviev     

Regularized Solutions of a Nonlinear Convolution Equation on the Euclidean Group

In this paper we apply Fourier analysis on the two and three dimensional Euclidean motion groups to the solution of a nonlinear convolution equation. First, we review the theory of the irreducible unitary representations of the motion group and discuss the corresponding Fourier transform of functions on the motion group. The main reasons why exact solutions of this convolution equation do not exist in many cases are discussed. Techniques for regularization of the problem and numerical methods for finding approximate solutions are presented. Examples are considered and approximate solutions are found.     

Hamiltonian Systems Derived from Constant Mean Curvature Surfaces in Hyperbolic Three-Space

We give a representation formula for surfaces of constant mean curvature in Euclidean or hyperbolic space, which is a natural generalization of Weierstrass-Enneper representation formula. The data (two functions) used in our formula should satisfy a certain system of differential equations. The system can be interpreted as an infinite dimensional Hamiltonian system. We investigate two finite-dimensional reductions in detail.