ON SOME SPECIAL CLASSES OF PRIME RINGS

Abstract

Given a non-zero cardinal α, a ring R is said to be SP(α) if a is the first cardinal for which every non-zero element of R has an insulator of cardinality less than α + 1.

It is shown that the class of SP(α) rings is a special class (in the sense of Andrunakievi?) for each α. A theorem of Groenewald and Heyman (also Desale and Varadarajan) to the effect that the class of all strongly prime rings is a special class is obtained as a corollary. Every SP(α) ring has an SP(α) rational extension ring with identity.     

A NOTE ON POLYNOMIAL RINGS OVER VON NEUMANN REGULAR RINGS

Abstract

Let R be an associative ring with 1. It is well known (see [1], [2]) that if R is commutative, then R is Yon Neumann regular (VNR) <=> the polynomial ring S = R[x] is semihereditary. While one of these implications is true in the general case, it is known that a polynomial ring over a regular ring need not be semihereditary (see [3]). In [4] we showed that a ring R is VNR <=> aS + xS is projective for each a ε R. In this note we sharpen this result and use it to show that if c is the ring epimorphism from R[x] to R that maps each polynomial onto its constant term, then R is Yon Neumann regular <=> the inverse image (under c) of each principal (right, left) ideal of R. is a principal (right. left) ideal of R[x] generated by a regular element. (Here an element is regular if and only if it is a non zero-divisor).     

ON A CLASSIFICATION OF PRIME RINGS

Abstract

We formalize the adjunction of maps of localized nilpotent spaces of the homotopy type of CW-complexes. Using the semilocalization theory of M. Bendersky, in which only the higher homotopy groups are localized, we obtain an adjunction theorem with fewer nilpotency conditions on the spaces. The two main theorems are in the form of a theorem on maps of triads by J. P. May.     

ON ANTISIMPLE GAMMA RINGS

ABSTRACT

In this note, we define the antisimple radical, A(M), of a Γ-ring M. A(M) is shown to be a special radical, and two characterizations of antisimple rings due to Szész are extended to Γ-rings. If R is the right operator ring of M, then A(R)* = A(M), where A(R) is the antisimple radical of R. If m,n are positive integers, then A(M_mn) = (A(M))_mn, where M_mn denotes the group m x n matrices over M, considered as a Γ_nm -ring with the operations of matrix addition and multiplication.     

ON THE STRUCTURE OF THE JACOBSON RADICAL OF GRADED RINGS

Abstract

We introduce a new large class of semigroups S including all locally finite, completely regular and strongly π-regular linear semigroups. For any semigroup S in the class and any S-graded ring R, the structure of the Jacobson radical of R is reduced to the radicals of subrings graded by the maximal subgroups of S. Many results on radicals follow from this reduction in a unified way. In two special cases the reduction is simplified.     

CLASSICAL QUOTIENT RINGS OF GROUP RINGS

Abstract

Throughout G will denote a free Abelian group and Z(R) the right singular ideal of a ring R. A ring R is a Cl-ring if R is (Goldie) right finite dimensional, R/Z(R) is semiprime, Z(R) is rationally closed, and Z(R) contains no closed uniform right ideals. We prove that R is a Cl-ring if and only if the group ring RG is a C1-ring. If RG has the additional property that bRG is dense whenever b is a right nonzero-divisor, then the complete ring of quotients of RG is a classical ring of quotients.     

零可换环的一些性质

本文刻画了零可换环的一些性质,同时将交换环上的一些结果推广到零可换环上.对于零可换环R 证明了: (1)R是强正则环当且仅当R中每个为零化子的本质左理想是左GP.内射模或R中存在一个极大左理想K,使得K中每个元索的零化子是左GP-内射模; (2)R是GPP-环当且仅当R是拟π-正则的GPF-环.     

零可换环的一些性质

本文刻画了零可换环的一些性质,同时将交换环上的一些结果推广到零可换环上.对于零可换环R证明了(1)R是强正则环当且仅当R中每个为零化子的本质左理想是左GP-内射模或R中存在一个极大左理想K,使得K中每个元素的零化子是左GP-内射模;(2)R是GPP-环当且仅当R是拟π-正则的GPF-环.     

RADICALS OF STRUCTURAL MATRIX RINGS

The concept of a structural matrix ring was introduced by van Wyk [8]. In [9] certain radicals of these matrix rings are studied. The purpose of this paper is to obtain similar results for a wider class of radicals.     

A NOTE ON THE g-PRIME RADICAL IN GAMMA RINGS

ABSTRACT

The g-prime radical of a Γ-ring M is equal to either the zero ideal or the prime radical of M. If the prime radical of M is a non-zero ideal, then the following three conditions are equivalent; (i) g-prime radical of M is equal to the prime radical of M; (ii) every g-prime ideal is a prime ideal; and (iii) every g-semiprime ideal is a semiprime ideal.     

THE ADDITIVE GROUPS OF RINGS WITH TOTALLY ORDERED LATTICE OF IDEALS

The object of this paper is to describe the additive groups of rings R satisfying the following condition: For any two ideals A,B in R either A u B, or B u A. Such rings will be called TOLI rings. The rings considered here are not necessarily associative or with identity.     

REGULARITIES AND SUBDIRECT PRODUCTS OF RINGS

Abstract

Structure theorems are obtained for certain radical classes of rings (including the Brown-McCoy radical class, the class of λ-rings, the class of E ₅-rings, the class of E ₆-rings and the class of f-regular rings) by generalizing the concept of a prime ideal.     

SOME SPECTRAL PROPERTIES OF MULTIPLIERS ON SEMI-PRIME BANACH ALGEBRAS

Abstract

We extend to arbitrary semi-prime Banach algebras some results of spectral theory and Fredholm theory obtained in [1] and [2] for multipliers defined in commutative semi-simple Banach algebras.     

NOTES ON NILPOTENCY OF NIL SUBRINGS OF ENDOMORPHISM RINGS OF MODULES

Abstract

A family K of right R-modules is called a natural class if K is closed under submodules, direct sums, infective hulls, and isomorphic copies. The main result of this note is the following: Let K be a natural class on Mod-R and M ε K. If M satisfies a.c.c. (or d.c.c.) on the set of submodules {N ? M: M/N ε K}, then each nil subring of End(M_R ) is nilpotent.     

TORSION-FREE ABELIAN GROUPS WITH FINITE RANK ENDOMORPHISM RINGS

Abstract

We show that if A and C are torsion-free abelian groups with ∩{ker f|f: A → C} = 0 = ∩{ker g|g: C → A}, and if A has a left Artinian quasi-endomorphism ring then A and C share a nonzero quasi-summand. Some consequences explored.     

ON THE COMMUTATIVITY OF PRIME RINGS WITH DERIVATION

Abstract

We study commutativity of prime rings R such that d(S) is central, where d is a non-zero derivation and S a suitably-chosen subset of R.     

SMOOTHNESS PROPERTIES OF REAL-VALUED FUNCTIONS BASED ON THEIR OSCILLATION

Abstract

We consider the following two selection principles for topological spaces:

Principle 1: For each sequence of dense subsets, there is a sequence of points from the space, the n-th point coming from the n-th dense set, such that this set of points is dense in the space;

Principle 2: For each sequence of dense subsets, there is a sequence of finite sets, the n-th a subset of the n-th dense set, such that the union of these finite sets is dense in the space.

We show that for separable metric space X one of these principles holds for the space C_p (X) of realvalued continuous functions equipped with the pointwise convergence topology if, and only if, a corresponding principle holds for a special family of open covers of X. An example is given to show that these equivalences do not hold in general for Tychonoff spaces. It is further shown that these two principles give characterizations for two popular cardinal numbers, and that these two principles are intimately related to an infinite game that was studied by Berner and Juhász.     

PRIME IDEALS IN RINGS WITH INVOLUTION

Abstract

Let R be a ring with involution *. We show that if R is a *-prime ring which is not a prime ring, then R is “essentially” a direct product of two prime rings. Moreover, if P is a *-prime *-ideal of R, which is not a prime ideal of R, and X is minimal among prime ideals of R containing P, then P is a prime ideal of X, P = X ∩ X* and either: (1) P is essential in X and X is essential in R; or (2) for any relative complement C of P in X, then C* is a relative complement of X in R. Further characterizations of *-primeness are provided.     

SOME RECENT RESULTS ON CATEGORIES OF R-SPACES AND PROBABILISTIC SPACES AND ON CATEGORICAL SPECTRA

The purpose of this paper is twofold: first, to present some recent results obtained by Romanian mathematicians in the field of general and categorical topology; second, to present some current research results obtained by the author in what may be called the topological study of a category. Accordingly, the paper is divided into two parts.

The author wishes to express his gratitude to the organizing committee of this Symposium for the kind invitation to present' this paper.     

GENERALISED IDEALS OF RINGS

Abstract

Using a general definition of a regularity for rings, F- and F- qausi-ideals of a ring are defined. These concepts are shown to be generalizations of ideals or one-sided ideals of a ring. An F-semi prime F—(F-quasi-) ideal of a ring R is also defined. F-regular rings are characterized in terms of F-semi prime F- (F-quasi-) ideals for a large class of polynomial regularities including some well known regularities. A more general characterization of the prime radical β(R) of a ring are given in terms of F—(F-quasi-) ideals.