一类特殊的有限循环环

证明了一类n阶(n=P_1P_2…p_m,p_i(i=1,2,…,m)互异为素数)环是有限循环环,并讨论了他们的结构及相关性质,最后给出了这类n阶环有零因子或有子域的充要条件.主要结果:P_1P_2…P_m阶环共有2^m个,它们是(p_(1m个,它们是(p_(1^k_1) p_(2k_1) p_(2^k_2)…p_(mk_2)…p_(m^k_m)Z)/(p_(1k_m)Z)/(p_(1^k_1+1)p_(2k_1+1)p_(2^k_2+1)…p_(mk_2+1)…p_(m^k_m+1)Z),其中k_i=0或1,1≤i≤m;阶是n=P_1P_2…p_m的环R可唯一分解为m个素数阶理想的直和,即R=〈α〉=(?);含pi(1≤i≤m)阶子域的P_1P_2…P_m阶环共有2k_m+1)Z),其中k_i=0或1,1≤i≤m;阶是n=P_1P_2…p_m的环R可唯一分解为m个素数阶理想的直和,即R=〈α〉=(?);含pi(1≤i≤m)阶子域的P_1P_2…P_m阶环共有2^(m-1)个,它们是p_(1(m-1)个,它们是p_(1^k_1) p_(2k_1) p_(2^k_2)…p_(mk_2)…p_(m^k_m)Z)/(p_(1k_m)Z)/(p_(1^k_1+1)p_(2k_1+1)p_(2^k_2+1)…p_(mk_2+1)…p_(m^k_m+1)Z),其.中k_i=0,k_j=0或1,1≤j≤m,j≠i.     

满足a+ab=a+b的幂等半环的结构

本文讨论了满足a+ab=a+b的幂等半环的结构,给出这种幂等半环是左零半环的伪强右正规幂等半环,并得出这种幂等半环与环的直积是左环的伪强右正规幂等半环.     

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 .     

Note on Sus̆kevic̆’s problem on zero divisors

We solve an old Sus?kevic?’s problem on right zero divisors in the ring T(∞,K) of infinite ?×? upper triangular matrices over a field K. In the solution we use a notion of strong linear independence.     

关于nZ的理想及商环

给出了nZ的全部理想、极大理想和素理想,并研究了nZ的商环的构造以及为域的条件,解决了Z<,n>的子域的存在和个数问题.     

Additive problems for integers with a given number of prime divisors

The asymptotics of sums of the form Στ(|bn−a|) (summation overn<N, ω(n)=k) is studied, whereω(n) is the number of distinct prime divisors ofn, andτ(n) is the number of all divisors. Translated fromMatematicheskie Zametki, Vol. 63, No. 5, pp. 749–762, May, 1998. In conclusion, the author wishes to express his gratitude to Professor N. M. Timofeev for valuable advice. This research was supported by the Russian Foundation for Basic Research under grant No. 96-01-00502.     

Redefined generalized fuzzy ideals of near-rings

With a new idea, we redefine generalized fuzzy subnear-rings(ideals) of a near- ring and investigate some of its related properties. Some new characterizations are given. In particular, we introduce the concepts of strong prime(or semiprime) (∈,∈∨q)-fuzzy ideals of near-rings, and discuss the relationship between strong prime(or semiprime) (∈,∈∨q)-fuzzy ideals and prime(or semiprime) (∈,∈∨q)-fuzzy ideals of near-rings.     

关于拟赋值环的一个刻画

Let R be a commutative ring without nil-factor. In this paper, we discuss the problem of quasi-valuation ring presented in the reference “Wang Shianghaw, On quasi-valuation ring, Northeast People‘s Univ. Natur. Sci. J., (1)(1957), 27-40”,when the quotient field of R is an algebraic number field or an algebraic function field, and we obtain a characterization of quasi-valuation rings.     

Properties of large prime divisors of numbers of the form p − 1

The main result of this paper is the fact that the fraction of primes p ≤ x satisfying the condition that p ? 1 has a prime divisor q > exp(ln x/ln ln x) and the number of prime divisors of q ? 1 essentially differ from ln ln(x/n), where n = (p ? 1)/q, tends to zero as x increases.     

LIE IDEALS, MORITA CONTEXT AND GENERALIZED （α β）-DERIVATIONS

A classical problem in ring theory is to study conditions under which a ring is forced to become commutative. Stimulated from Jacobson＇s famous result, several tech- niques are developed to achieve this goal. In the present note, we use a pair of rings, which are the ingredients of a Morita context, and obtain that if one of the ring is prime with the generalized （α β）-derivations that satisfy certain conditions on the trace ideal of the ring, which by default is a Lie ideal, and the other ring is reduced, then the trace ideal of the reduced ring is contained in the center of the ring. As an outcome, in case of a semi-projective Morita context, the reduced ring becomes commutative.     

Boundedness for Some Rationally Connected Threefolds in ℙ6

We prove boundedness of rationally-connected threefolds in ?⁶ under some extra-assumptions.     

一类无穷小(大)量的判别法及其应用

将级数敛散性判别法中的D’Alembert和Cauchy判别法移植到无穷小(大)数列上,可得到关于无穷小(大)数列的D’Alembert和Cauchy判别法,从而解决无穷小(大)数列的判别问题.     

Semirings which are unions of rings

Sernirings which are a disjoint union of rings form a variety S which contains the variety of all rings and the variety of all idempotent sernirings, and in particular, the variety of distributive lattices. Various structure theorems are established which bring insight into the structure of the lattice of subvarieties of S.``