LR-normal orthogroups

A new kind of regular orthogroups, namely, the LR-normal orthogroups is introduced and investigated. In particular, we will introduce the gearing techniques for fitting semigroup components on a semilattice in the construction of LR-normal orthogroups.     

LR-normal orthogroups

A new kind of regular orthogroups, namely, the LR-normal orthogroups is introduced and investigated. In particular, we will introduce the gearing techniques for fitting semigroup components on a semilattice in the construction of LR-normal orthogroups.     

左半正则纯整群并半群的左半织积结构

作为拟Ｃ－半群的推广,本文定义了左半正则纯整群并群,给出了它的左半织积结构。讨论了两类特殊的右（右）半正则纯整群并半群,得出了左（右）半正则纯整群并半群类与拟Ｃ－半群类之间的关系。     

Maximal Normal Orthogroups in Rings Containing No Infinite Semilattices

Let R be a ring regarded as a multiplicative semigroup which contains no infinite subsemilattices. We investigate subsemigroups of R which are normal orthogroups, and present a construction from which all such maximal normal orthogroups can be obtained. In particular, we construct all maximal normal orthogroups of matrices over a field under matrix multiplication.

Communicated by D. Easdown.     

关于同余交换纯正群并的构造与分类

本文讨论同余交换纯正群并的构造与分类。文中将该类半群给出分解方法，指出该类半群是它的左，右分量的织积。接着给出该类半群的完整分类，指出共有２０类并给出各类的构造，上述结论还用来讨论同余交换带，文中给出所有２９个同余交换带的构造并证明同余交换带都是有限的且元素个数不超过１３．     

New Braided Crossed Categories and Drinfel'd Quantum Double for Weak Hopf Group Coalgebras

A simple and nice structure theorem for orthogroups was given by Petrich in 1987. In this paper, we consider a generalized orthogroup, that is, a quasi-completely regular semigroup with a band of idempotents in which its set of regular elements, namely, RegS, forms an ideal of S. A method of construction of such semigroups is provided and as a result, the Petrich structure theorem of orthogroups becomes an immediate corollary of our theorem on generalized orthogroups. An example of such generalized orthogroup is also constructed. This example provides some useful information for the construction of various kinds of quasi-completely regular semigroups.     

两类完全正则半群的同态和同余

本文研究了密群的同态和纯正群的幂等元分离同余.定义了密群的半格类之间的一种映射,利用该映射,半格的同态及完全单半群上的同态刻画了密群间的同态.利用群核正规系讨论了纯正群的幂等元分离同余.并给出其一种简单的表示形式.     

Characterizations of certain completely regular varieties

We characterize orthogroups, local orthogroups and (left,right) cryptogroups within completely regular semigroups by means of absence of certain kind of subsemigroups. For each of these varieties V, we determine the complete set of minimal non-V -varieties. For each of the latter varieties, we determine the lattice of its subvarieties. We then give a generating semigroup and a basis of its identities for every variety which occurs in this way. The subvariety lattices are illustrated by three diagrams.     

Characterizations of certain completely regular varieties

Abstract. We characterize orthogroups, local orthogroups and (left,right) cryptogroups within completely regular semigroups by means of absence of certain kind of subsemigroups. For each of these varieties V , we determine the complete set of minimal non-V -varieties. For each of the latter varieties, we determine the lattice of its subvarieties. We then give a generating semigroup and a basis of its identities for every variety which occurs in this way. The subvariety lattices are illustrated by three diagrams.     

具有逆断面的纯正群的构造

本文用具有半格断面的带和Clifford半群给出具有逆断面的纯正群的一个构造定理.     

纯正群并的结构

本文主要利用带B=（Y;B_α）,Clifford半群G=[Y;G_α,θ_a,β和对于α∈Y,群同态σ_α:G_a→Aut（αBα）来构造纯正群并.     

纯正半群上的同余扩张(二)

刻画半群上的同余及其扩张是半群的代数理论中的一个非常重要的课题（参见［1－5］）本文在[6]讨论了带上的同余的正规性和不变性以及在其Hall半群上的扩张的基础上,从同余扩张的角度刻划了完全正则的纯正半群的特征（定理26）,给出了一个纯正半群的带上的所有同余都可以扩张到这个纯正半群的充分必要条件．     

Global determinism of normal orthogroups

If S is a semigroup, the global (or the power semigroup) of S is the set \(\mathcal {P}(S)\) of all nonempty subsets of S equipped with the naturally defined multiplication. A class \(\mathcal {K}\) of semigroups is globally determined if any two semigroups of \({\mathcal {K}}\) with isomorphic globals are themselves isomorphic. We study properties of globals of normal orthogroups and show, in particular, that the class of normal orthogroups is globally determined.     

乘法半群为左正规纯正群的半环

研究了加法半群为半格,乘法半群为左正规纯正群的半环．证明了此类半环（S,＋,．）可以嵌入到半格（S,＋）的自同态半环中．构造S的一个特定的偏序关系,得到了（S,·）上的自然偏序与所构造偏序相等的等价条件．     

加法半群为正规纯整群的半环

加法半群为正规纯整群的半环类记为ONBG,本文主要研究了ONBG中半环的一些性质和次直积分解.     

Completely regular semigroups in the variety generated by the bicyclic semigroup

We shall show that a completely regular semigroup is in the semigroup variety generated by the bicyclic semigroup if and only if it is an orthogroup whose maximal subgroups are abelian. Therefore the lattice of subvarieties of the variety generated by the bicyclic semigroup contains as a sublattice a countably infinite distributive lattice of semigroup varieties, each of which consists of orthogroups with maximal subgroups that are torsion abelian groups. In particular, every band divides a power of the bicyclic semigroup.Presented by B. M. Schein.     

Ortho-u-monoids

In this paper, we study the class of ortho-u-monoids which are generalized orthogroups within the class of E(S)-semiabundant semigroups. After introducing the concept of (∼)-Green’s relations, and obtaining some important properties of (∼)-Green’s relations and super E(S)-semiabundant semigroups, we have given the semilattice decomposition of ortho-u-monoids and a structure theorem for regular ortho-u-monoids. The main techniques that we used in the study are the (∼)-Green’s relations, and the semi-spined product of semigroups.     

WLR-regular orthogroups

A regular orthogroup S with the property that D _e =R _e or D _e =L _e for any idempotent e∈S is called a WLR-regular orthogroup. In this paper, we give constructions of such semigroups in terms of spined products of left and right regular orthogroups with respect to Clifford semigroups. WLR-cryptogroups and its special cases are also investigated. Research supported by General Scientific Research Project of Shanghai Normal University No. SK200707.