ISSN:0092-7872    

DOI:10.1080/00927879908826510

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

In this paper we show that the Rees valuation rings, of a finitely generated, torsion-free moduleMover a two-dimensional regular local ring are precisely the Rees valuation rings of the rank(M)-th Fitting invariant of M. The technical tools used are quadratic transforms and Buchsbaum-Rim multiplicity.

ISSN:0092-7872    

DOI:10.1080/00927879908826511

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

We prove that certain algebra quotients of Hopf algebras are twisted Hopf algebras. On the other handuq(sl(2)) is a crossed product of a central subalgebra with a quotient Ʉ, whenqis a root of 1. Using the cocycle involved in this crossed product we construct non-trivial complex cocycles τ and we find the isomorphism classes of the corresponding twisted Hopf algebrasτɄ. These provide complex projective representations of Ʉ which are not ordinary representations.

ISSN:0092-7872    

DOI:10.1080/00927879908826512

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879908826513

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

We investigate a special relation between finite partition lattices and distributive lattices. This will allow us to explore the close relationship between a class of torsionfree Abelian groups (the subclass of the class of Butler groups consisting ofB(1)- groups) and a category of order-preserving morphisms mapping partition lattices into distributive lattices.

ISSN:0092-7872    

DOI:10.1080/00927879908826514

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

Ce travail est consacré à I'étude du spectre d'un anneau intermédiaireRentre un anneau intègre dénombrableDet I'anneau de polynômesD[x,y,z]: la construction deRest principalement baséc sur un exemple de Wadsworth. En conséquence, on apporte une réponse positive à une question: existe-t-il un anneau intermédiaire quine soit pas localement de Jaffard entre un corpsket unek-algébre de type fini?.

ISSN:0092-7872    

DOI:10.1080/00927879908826515

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

We show that, under ◊, an abelian group may split its double dual and yet not be dual. The construction technique simplifies to give an example of a reflexive groupAsuch that bothAandA*are strongly ℵ1-free of cardinality ℵ1.

ISSN:0092-7872    

DOI:10.1080/00927879908826516

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

It is known that every complex of leftR-modules has an exact cover. We consider the question of findingRfor which every complex of left i?-modules has an exact envelope. We first give a simple proof that for everyRevery complex of leftR-modules has a special exact preenvelope and then use this to show that the left perfect rings are thoseRfor which every complex has an exact envelope. So, for example, this result holds for all artinian rings.

ISSN:0092-7872    

DOI:10.1080/00927879908826517

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

A tag module is a generalization, in any abelian category, of a torsion abelian group. The theory of such modules is developed, it is shown that countably generated tag modules are simply presented, and that Ulm's theorem holds for simply presented tag modules. Zippin's theorem is stated and proved for countably generated tag modules.

ISSN:0092-7872    

DOI:10.1080/00927879908826518

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor

摘要:

Maximal commutative subalgebras of the algebra of n by n matrices over a field k very rarely have dimension smaller than n. There is a (B, N)-construction which yields subalgebras of this kind. The Courter's algebra that is of this kind was shown a (B, N)-construction whereBis the Schur algebra of size 4 andN=k4. That is, the Courter's algebra is isomorphic toB⋉ (k4)2, the idealization of (k4)2. It was questioned how many isomorphism classes can be produced by varying the finitely generated faithfulB-moduleN. In this paper, we will show that the set of all algebrasB⋉N2fall into a single isomorphism class, whereBis the Schur algebra of size 4 andNa finitely generated faithfulB-module.

ISSN:0092-7872    

DOI:10.1080/00927879908826519

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1999

数据来源: Taylor