摘要:

A radical classRpartitions a class of ringsTif for every T ε T either R(T) = 0 orR(T) = T. Given any class of rings C, Stewart [8] defines the class of almostC-rings, A(C), to be all those rings every non identity homomorphic image of which is inC. He then defines C to be the class of all rings S where S is the heart of a ring A with A/S in C. He then considers the general question: what radical classes partition the class of almost C-rings where C has certain properties. With the aid of M*-rings introduced in this paper we can generalize some of Stewart's results and obtain more natural partitions.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632275

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Prime and semiprime bi-ideals in associative rings are defined. This provides a setting for a generalization of the well-known theorem that a commutative ring is Von Neumann regular iff every ideal is semiprime.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632276

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Let G be an abelian group and g ε G; for an abelian group A, define TA = {a ε A: g⊗a=0 in G⊗A}. T is called the tensor-induced preradical determined by the pair (G,g). In this work a complete description of T is given in terms of the order of g and its finitary Ulm-sequence.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632277

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The aim of this paper is to describe some “topological” subclasses of the class of all semi-topological functors. This is done by considering intersections of certain classes: on the one hand, the classes of all semi-topological functors, all topologically-algebraic functors and all regular functors; and on the other hand, the class of all discrete functors (see [6]). The relations between these and other classes of functors are given along with the necessary examples. Finally, the resulting intersections are described by giving representations of the functors that belong to them.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632278

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In this paper, the relation between the notion of a discrete functor (see [4]) and the notion of a fine functor (see [1]) is examined. As a generalization of the notion of a F-fine object (see [1]), discrete functors T:A→Xare used to defineK-fine objects, whereKis a class ofA-objects. It is shown that if T is in addition semi-topological, then (as for F-fine objects in a topological category, see [1]) the class ofK-fine objects determines a bicoreflective subcategory ofA. Moreover, it is shown that in co-complete, co-(well-powered) categories, the existence of bicoreflective subcategories is equivalent to the existence of functors that are both discrete and semi-topological.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632279

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A finite element method for solving the wave equation with couples boundary conditions is presented. In this approach finite elements are applied globally with respect to space and simultaneously but locally with respect to time. This gives rise to a single-step method in time. The method is a practical and economic one and the numerical results obtained compare favourably with the available analytic solution.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632280

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

We show that left IF rings (rings such that every injective left module is flat) have certain regular-like properties. For instance, we prove that every left IF reduced ring is strongly regular. We also give characterizations of (left and right) IF rings. In particular, we show that a ring R is IF if and only if every finitely generated left (and right) ideal is the annihilator of a finite subset of R.

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632281

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Geometric methods for systems of partial differential equations and multiple integral problems in the calculus of variations lead naturally to differentiable manifolds that resemble fiber bundles but do not possess a structure group; in terms of local coordinates, π:B→Mn|(xi, qα)→(xi), dim(B) = N + n, dim(Mn) = n. The standard notions of horizontal distributions, horizontal and vertical subspaces of T(B), T(B) = V(B) ⊕ H(B), horizontal lifts of curves in Mn, and horizontal and vertical dual subspaces with Λ1(B) = V*(B) ⊕ H*(B) are shown to be well defined in B. The absence of a structure group is compensated for by an analysis based on the homogeneous ideals V and H that are generated by the canonical bases of V*(B) and H*(B), respectively. The differential system constructed from the generators of the horizontal ideal is shown to lead to a unique system of connection 1-forms and torsion 2-forms under the requirements that they have vacuous intersections with the horizontal ideal. The horizontal ideal is shown to be completely integrable if and only if the torsion 2-forms vanish throughout B, in which case the curvature 2-forms are congruent to zero mod H, and the curvature 2-forms are shown to have a vacuous intersection with H if and only if the horizontal distribution is affine. The paper concludes with a study of the mapping properties of the connection, torsion and curvature. These are significantly more general than those of a fiber bundle since the absence of a structure group allows mappings of the form 'xi= φi(x,q), 'qα= φα(x,q).

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632282

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632283

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1983.9632284

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor