关于线性丢番图方程的Frobenius问题

本文考虑线性丢番图方程a_1x_1+…+a_kx_k=b的非负整数解的存在性问题.为解答Frobenius开问题,对于k2,给出整数G(a_1,…,a_k)的表示形式,该整数是使得b≥G a(_1,…,a_k)时,上述丢番图方程总存在非负整数解的最小整数.     

关于丢番图方程ax2+by2=cz2+dw2的整数解

数论中作为勾股定理的推广曾讨论过方程x2 +y2 =z2 +w2 ( 1 )的整数解 (如文 [1 ]、[2 ]) ,文 [2 ]得到了方程 ( 1 )满足 ( x,y,z,w) =1的全部整数解的一组公式 ,但表达式不够简洁。本文将其推广 ,考虑更一般的这类四元二次丢番都方程ax2 +by2 =cz2 +dw2 ( 2 )其中 a,b,c,d均为正整数 ,( a,b,c,d) =1。当知道它的一组不全为零的整数解时 ,来导出它满足 ( x,y,z,w) =1的全部整数解的公式。按所设 ,显然 z,w不会全为 0 ,不妨设 w≠ 0 ,从而方程 ( 2 )可变为a( xw) 2 +b( yw) 2 -c( zw) 2 =d令 X=x/ w,Y=y/ w,Z=z/ w,得a X2 +b Y2 -c Z2 =d …     

两个丢番图方程y~2=nx(x~2±1)

本文利用Ljunggren,Cohn,Bennett和Walsh以及陈建华等人的结果,给出了两个丢番图方程正整数解的解数上界和有效算法.     

两个丢番图方程y~2=nx(x~2±1)

本文利用Ljunggren,Cohn,Bennett和Walsh以及陈建华等人的结果,给出了两个丢番图方程正整数解的解数上界和有效算法.     

关于丢番图方程中的柯召—Terjanian—Rotkiewicz方法

1962年,柯召[1]为了证明丢番图方程 x~2-1=y~p,p>3是素数,(1)无整数解,提出了计算Jacobi符号 (Q_p(y)/Q_q(y))来处理丢番图方程的方法,这里Q_n(y)=y~n 1/y 1,2十n.后来,1977年,Terjanian[2]为了证明丢番图方程     

关于丢番图方程X~3±1=1267y~2的整数解

关于丢番图方程x³±1=1267y3±1=1267y²的初等解法至今仍未解决.主要利用递归序列、同余式、平方剩余、Pell方程的解的性质、Maple小程序,证明了丢番图方程x2的初等解法至今仍未解决.主要利用递归序列、同余式、平方剩余、Pell方程的解的性质、Maple小程序,证明了丢番图方程x³-1=1267y3-1=1267y²有整数解(x,y)=(1,0),(60817,±421356),而丢番图方程x2有整数解(x,y)=(1,0),(60817,±421356),而丢番图方程x³+1=1267y3+1=1267y²仅有整数解(x,y)=(-1,0).     

线性丢番图方程的一个数值解法

线性丢番图方程的一个数值解法薛方，郑辉，范小寅（北京大学数学系１００８７１）１引言本文讨论如何求出正整系数线性丢番图方程的全部非负整数解：给定向量ａ＝（ａ１，ａ２，…，ａｎ），ａｉ∈Ｎ；及ｎ∈Ｎ任给，求全体可能向量Ｘ＝（ｘ１，ｘ２，…，ｘｎ）使得ａ·...     

关于丢番图方程1+5~x+2~y5~z11~u=2~v·11~w,yvw>0,x+z>0的解

讨论了丢番图方程1+X+Y=Z的一个特殊情形.借助计算机,用初等方法给出了指数丢番图方程1+5~x+2~y5~z11~u=2~v·11~w,yvw>0,x+z>0的全部非负整数解.     

丢翻图方程x~2+a~2=2y~n解法的计算研究

本文研究了一类丢番图方程的解.利用对Thue方程解的估计和方程解的连分式展开,获得了所求丢番图方程解的个数、解上界的估计和一般的求解算法.最后利用该算法给出了1≤a≤108的所有解.     

关于丢番图方程 χ^3一У^6=3pz^2的整数解

设p=5（mod 6）为素数．证明了丢番图方程χ^3一У^6=3pz^2。在p=5（mod 12）为素数时均无正整数解;在P=11（mod 12）为素数时均有无穷多组正整数解,并且还获得了该方程全部正整数解的通解公式,同时还给出了该方程的部分整数解．     

Modified Equations for Stochastic Differential Equations

We describe a backward error analysis for stochastic differential equations with respect to weak convergence. Modified equations are provided for forward and backward Euler approximations to Itô SDEs with additive noise, and extensions to other types of equation and approximation are discussed.     

同调方程

设Ｒ是左、右凝聚环,Ｒ~ωＲ是一个忠实平衡自正交双模．对有限表现左Ｒ－模Ａ和正整数ｎ,本文研究了形如,　的同调方程．给出了模范畴为有限表现右Ｒ-模｝是子模闭的充要条件,并举例说明了该模范畴并非总是子模闭的,     

Convergence of Compressible Euler-Maxwell Equations to Compressible Euler-Poisson Equations

In this paper,the convergence of time-dependent Euler-Maxwell equations to compressible Euler-Poisson equations in a torus via the non-relativistic limit is studied. The local existence of smooth solutions to both systems is proved by using energy esti- mates for first order symmetrizable hyperbolic systems.For well prepared initial data the convergence of solutions is rigorously justified by an analysis of asymptotic expansions up to any order.The authors perform also an initial layer analysis for general initial data and prove the convergence of asymptotic expansions up to first order.     

On Some Model Equations of Euler and Navier-Stokes Equations

The author proposes a two-dimensional generalization of Constantin-Lax-Majda model. Some results about singular solutions are given. This model might be the first step toward the singular solutions of the Euler equations. Along the same line (vorticity formulation), the author presents some further model equations. He possibly models various aspects of difficulties related with the singular solutions of the Euler and Navier-Stokes equations. Some discussions on the possible connection between turbulence and the singular solutions of the Navier-Stokes equations are made.     

Partial Difference Equations Analogous to the Cauchy-Riemann Equations and Related Functional Equations On Rings and Fields

Let (S, #, *) be an algebraic structure where # and * are binary operations with identities on the set S. Let (G, +) be an abelian group. We consider the functional equation (i) $$f(x * t, y)+ g(x, y\ \sharp\ t) = h(x, y)\ {\rm for\ all}\ x, y, t \in S,$$ where ?,g,h :S × S → G. As an application of (i) we solve $$f(x + t, y)- f(x, y) = -b(f(x, y+t)- f(x,y))\ {\rm for\ all}\ x, y, t \in S,$$ where ? :S × S → K (a field), and b ∈ K is a constant and b ≠ 0, ±1. If b = i, the pure imaginary unit, S = R and K = C, then the above equation may be considered as a discrete analogue of the Cauchy-Riemann equations. When (R, +, ?) is a commutative ring with 1, the functional equation (ii) $$\phi(y+xt)-\phi(xy+xt)=\phi(y+x)-\phi(xy+x)$$ for all x,y,t ∈ R, where ? : R → G, is basic to the general solutions of (i). We solve (ii) on certain rings and fields.     

Global Results for the Rarita-Schwinger Equations and Einstein Vacuum Equations

We prove global existence and uniqueness of solutions to theRarita-Schwinger evolution equations compatible with the constraints.We use a gauge fixing for the Rarita-Schwinger equations forhelicity 3/2 fields in curved space that leads to a straightforwardHilbert space framework for their study. We explain how theseresults might be applied to the global analysis of the fullEinstein vacuum equations and provide a complete analysis asa basis for such applications. These and a programme for developinga scattering/inverse scattering transform for the full Einsteinequations are discussed. 1991 Mathematics Subject Classification:83C60, 35Q75, 83C05, 35L45.     

变更Boussinesq方程和Kupershmidt方程的多孤子解

使用王明亮引进的齐次平衡方法,求出了变更Boussinesq方程和Kupershmidt方程的多孤子解,而王明亮给出的变更的Boussinesq方程的单孤子解仅是上述结果的一种特殊情况.