某些环的结构

Jacobson的著名定理指出,若结合环R满足:对任意x∈R均有整数m(x)>1使x~[m(s)]=x,则R同构于一些域的亚直接和.Putcha与Yaqub推广了此结果.定义x_1,…,x_n的一个字w(x_1,…,x_n)为一个乘积,其每个因子都是某个x_i(i=1,…,n).于是,一个多项式f(x_1,…,x_n)则具形     

某些特殊分式方程的解法

初中代数习題中,有些較为特殊的分式方程,在求它們的根时,如果按照一般解法,不仅演算过程复杂,而且容易遺根。作者对这些特殊的分式方程采用以下的解法,可以簡化演算过程,又不致遺根。定理1.在两个相等的分式中,如果分子相同,那末分子为零或者两个分母相等。 証.設f(x,y,…,z)/g(x,y,…,z)=f(x,y,…,z)/g_1(x,y,…,z)。此分式的值可能有下列两种情况出現:     

某些高维非线性周期系统的周期解

本文用李雅普诺夫函数法和 Brouwer 不动点定理究研某些高维非线性周期系统的周期解问题,得到了一些存在唯一稳定周期解的充分条件。     

某些特殊三角形的复数表示

在中学代数里我们学过复数,我们知道,复数可用平面上的向量或点来表示,利用复数的基本运算及其几何意义,已经解决了许多平面几何问题.本文对此不作详细介绍,而限于讨论怎样用复数表达一个三角形     

某些特殊循环矩阵的逆

<正> 文[1]给出了某些特殊循环矩阵逆的求法。本文就此深入讨论给出一些简便方法。设循环矩阵A为则D也为循环矩阵,有时称为基础循环矩阵.令D~k=(_(I_k)~0 _0~(I_(n-k)),(k=1,2,…,n—1),D~n=I.则循环矩阵A可表示为     

某些特殊循环矩阵的逆

贵刊1986年第10期,姚存峰给出了求循环矩阵的逆矩阵的一个方法。此法虽然解决了循环矩阵的求逆问题,但在实际应用中因有大量的三角函数运算等问题,因此此法使用起来不太方便.本文就某些特殊类型的循环矩阵的求逆问题进行探讨,给出一些简便方法. 设循环矩阵A为     

某些微分差分方程的周期解

本文给出了微分差分方程及 x′(t)=-g(x(t))F(x(t),x(t-1))x′(t)=-g(x(t))F(x(t),x(t-1),…,x(t-n))存在非平凡周期解的充分条件。     

某些周期微分方程的亚纯解

本文讨论了两类具周期亚纯系数的微分方程(1．2)，(1．3)亚纯解的表示，得到两个Malmqusit 型定理(定理1，定理3)，即方程(1．2)，(1．3)的亚纯解分别是其系数类的子类。     

环面上动力系统的某些性质

本文讨论了曲面动力系统中三个方面的主题,即,环面上具有积分不变量的动力系统轨线的拓扑分类,这类系统的各态历经性质,以及环面上动力系统的唯一各态历经性.文章简要地叙述了在这些主题上最近得到的新结果.     

某些环的交换性条件

设Ｚ（Ｒ）是环Ｐ的中心，本文证明了下列的结果：（１）若Ｒ是一个半单纯环，且对任意ａ，ｂ∈Ｒ，都存在一自然数Ｋ＝Ｋ（ａ，ｂ），一含有Ｘ￣２和ｎ＝ｎ（ａ，ｂ）（≥Ｋ）个ｙ的字ｆ＿Ｘ（ｘ，ｙ）及一整系数多项式使得则Ｒ是交换环；（２）若Ｒ是一个Ｂａｅｒ半单纯环，且对任意的ａ．ｂ∈Ｒ，都存在一自然数Ｋ＝Ｋ（ａ，ｂ）≤ι，一含有ｘ￣２和ｎ＝ｎ＇（ａ，ｂ）（≥Ｋ）个ｙ的ｆ＿Ｘ（ｘ，ｙ）及一整系数多项式使得其中ι是一固定的自然数，那么，Ｒ是一个交换环。     

关于周期环与Jacobson环的几个定理

A ring R is called a periodic ring, if for every x∈R there exist two distinct positive integers m(x) and n(x) such that x^m(x)=x^n(x)(cf. [1]), in particularly, if m(x) = 1 for any x∈R. then this periodic ring is called a Jacobson ring (cf. [2]).In this paper, a necessary and sufficient condition for a ring to be a Jacobson ring is given and some necessary and sufficient conditions for a periodic ring or a Jacobson ring to be a field are also given.     

有限结合环类中的特殊根

设Ω是有限结合环类中全部弱单环组成的环类，Ω１∪Ω２＝Ω，Ω１∩Ω２＝Φ，在有限结合环类中，我们证明了ＬΩ１＝ＵΩ２可以成立，并给出等式成立的充要条件．使用这个结论，我们可以证明，在有限结合环类中，超幂零根是特殊根．     

On the Construction of d-Continuous Modules over Some Special Rings

ＯｎｔｈｅＣｏｎｓｔｒｕｃｔｉｏｎｏｆｄ－ＣｏｎｔｉｎｕｏｕｓＭｏｄｕｌｅｓｏｖｅｒＳｏｍｅＳｐｅｃｉａｌＲｉｎｇｓ￥ＣｈｅｎＪｉｎｊｉａｎ（ＧｕａｎｇｄｏｎｇＮａｔｉｏｎａｌＩｎｓｔｉｔｕｔｅ）Ａｂｓｔｒａｃｔ：Ｉｎｔｈｅｐｅｐｅｒ，ｗｅｕｓｉｎｇ...     

一个二元周期函数类的正交投影宽度

本文得到了二元周期可微函数类△_p~r在空间L_q(T~2)中的正交投影宽度d1/N(△_p~r,L_q)的渐近精确阶．     

A Note on Rings and Modules Graded by Some Special Groups

In this note we prove that the prime madicals of some graded rings and the scoles of some graded modules are also graded. The results on the relations between the prime radical and the graded prime radical are also presented. Moreover, the relations between a graded ring and its initial subring are studied.     

一类有限环

本文指出了文 [5 ]的一些错误 ,给出了文 [5 ]定理 1的一个反例 .并给出了一类交换环的等价条件 .     

结合环类中的E-单环

在全部结合环类中，对幂等根Ｅ，定义了Ｅ－单环．本文给出Ｅ－单环的一个刻画．     

A Remarkable Class of Rings

We consider a remarkable class of rings, which we call corpids, that is the rings (K, +, ·), such that (K, ·) is an inverse semigroup (or groupid, which is the name used by Tallini (Ann Math 71:295–322, 1966). We prove several theorems concerning this structure, an order relation which allows us to formulate characterization theorems. We define the notion of simple idempotent and prove theorems about zero-divisors, idempotents, subcorpids, ideals and characteristic in a corpid.     

A Class of Quasipolar Rings

An element a of a ring R is called J-quasipolar if there exists p ² = p ∈ R satisfying p ∈ comm²(a) and a + p ∈ J(R); R is called J-quasipolar in case each of its elements is J-quasipolar. The class of this sort of rings lies properly between the class of uniquely clean rings and the class of quasipolar rings. In particular, every J-quasipolar element in a ring is quasipolar. It is shown, in this paper, that a ring R is J-quasipolar iff R/J(R) is boolean and R is quasipolar. For a local ring R, we prove that every n × n upper triangular matrix ring over R is J-quasipolar iff R is uniquely bleached and R/J(R) ? ?₂. Moreover, it is proved that any matrix ring of size greater than 1 is never J-quasipolar. Consequently, we determine when a 2 × 2 matrix over a commutative local ring is J-quasipolar. A criterion in terms of solvability of the characteristic equation is obtained for such a matrix to be J-quasipolar.     

Cohen-Macaulayness of Special Fiber Rings

Abstract

Let (R, 𝔪) be a Noetherian local ring and let Ibe an R-ideal. Inspired by the work of Hübl and Huneke, we look for conditions that guarantee the Cohen-Macaulayness of the special fiber ring ? = ?/𝔪? of I, where ? denotes the Rees algebra of I. Our key idea is to require ‘good’ intersection properties as well as ‘few’ homogeneous generating relations in low degrees. In particular, if Iis a strongly Cohen-Macaulay R-ideal with G _?and the expected reduction number, we conclude that ? is always Cohen-Macaulay. We also obtain a characterization of the Cohen-Macaulayness of ?/K? for any 𝔪-primary ideal K. This result recovers a well-known criterion of Valabrega and Valla whenever K = I. Furthermore, we study the relationship between the Cohen-Macaulay property of the special fiber ring ? and the Cohen-Macaulay property of the Rees algebra ? and the associated graded ring 𝒢 of I. Finally, we focus on the integral closedness of 𝔪I. The latter question is motivated by the theory of evolutions.