摘要:

LetSbe a completely simple semigroup represented as a Rees matrix semigroupM(I,G,P) with normalized sandwich matrixP. On the congruence latticeC(S) ofSwe consider the relationsTi,KandTrwhich identify congruences with the same left trace, kernel and right trace, respectively. These are equivalences whose classes are intervals. The upper and lower ends of these intervals induce the following operators onC(S)Tl, K, Tr, tl, kandtr.We construct here the semigroup generated by these operators as a homomorphic image of a semigroup given by generators and relations and demonstrate the minimality of the latter.

ISSN:0092-7872    

DOI:10.1080/00927870008827040

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827041

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827042

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827043

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827044

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

The quasivarietyconsists of all [all finite] semigroups which can be embedded into a semigroup of order-preserving mappings on a chain [on a finite chain]. We give two abstract descriptions of, one using a special construction, and another using standard conditions (quasi-identities).

ISSN:0092-7872    

DOI:10.1080/00927870008827045

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

LetKbe a commutative ring, let ▵ be an abelian group, and let ϵ:▵x▵→Kbe a commutation factor over ▵.A ▵ gradedK-algebra is said to be ϵ-commutative if its ϵ-bracket is identically zero, (K,ϵ) derivations from a given ϵ-commutative ▵-gradedK-algebraAinto bimodules are studied. It is proved that for each λϵ▵ there exists a universal initial (k,ϵ)-derivation of degree λ ofA. For each λϵ▵ a natural module of (K, ϵ, λ)-differentials ofAalong with a differential map is constructed. It is proved that each derivation ofAcanonically equipps this module with a structure of differential module. Applications and examples are given. It is shown that the first order exterior differentials which are known from the theory of smooth graded manifolds are universal initial homogeneous derivations of the sort considered hereby.

ISSN:0092-7872    

DOI:10.1080/00927870008827046

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

The paper concerns the question of A. Shalev: is it true that every collapsing group satisfies a positive law? We give a positive answer for groups in a large classC, including all soluble and residually finite groups.

ISSN:0092-7872    

DOI:10.1080/00927870008827047

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827048

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

Leta,bbe singular endomorphisms of a. finite dimensional vector spaceVand denote bySathe semigroup generated by all the elementsg-1ag, wheregϵAut(V).The aim of this paper is to prove thatbϵSaif and only if rank(b) ≥ rank(a).

ISSN:0092-7872    

DOI:10.1080/00927870008827049

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor