半群的模糊同余扩张

本文引入半群的模糊同余扩张的概念,给出了模糊同余扩张的同态性质,同时,本文研究了带有模糊同余扩张性质的半群类,证明了一个半群S有模糊同余扩张性质当且仅当S有同余扩张性质,最后进一步给出 有模糊同余张张性质的半群类的特征。     

强双单严格纯正半群上同余的刻划

本文利用正则半群同余的概念，找到了任一强双单严格纯正半群Ｓ的一个正规子半群ＮＫ和Ｅ上的一个正规同余ГＰ，证明了Ｓ的任何一同余可由余偶确定，从而给出了Ｓ上任一同余的一个具体刻划。     

幺半群的半直积及其同余

给出了两个幺半群的半直积是Ｃｌｉｆｆｏｒｄ半群的充要条件及其结构。并讨论了逆半群半直积的Ｇｒｅｅｎ关系、最小群同余和极大幂等元分离同余。     

含幺Clifford半群上的Rees矩阵半群的同余和正规加密群结构

给出了含幺Clifford半群上的Rees矩阵半群S的正规加密群结构,证明了在含幺Clifford半群上的Rees矩阵半群S上以下两个条件是等价的:(1)S上的同余ρ是完全单半群同余;(2)S上的同余ρ和S上的相容组之间存在保序双射.最后还证明了S上的完全单半群同余所构成的同余格是半模的.     

半群的半直积及其同余

给出了两个幺半群的半直积是Ｃｌｉｆｏｒｄ半群的充要条件及其结构．并讨论了逆半群半直积的Ｇｒｅｅｎ关系、最小群同余和极大幂等元分离同余．     

Γ—正则半群上的若干同余

本文首先给出了Γ－正则半群上的群同余刻划。然后定义了Γ－逆半群的幂等分离核正规系，证明了Γ－逆半群上的幂等分离核正规系决定一个Γ－逆半群上的等分离同余，及Γ－逆半群上的幂等分离同余核是一个等分离核正规系。     

夹心半群S(X,Y,θ)上的α-同余

本文讨论了夹心半群T(X,Y,θ)上的α-同余与集合Y上Tθ-等价关系之间的联系,证明了对于每个Tθ-等价关系E,夹心半群同余格C(T(X,Y,θ))的完全子格γ-1(E)中的最大元是一个α-同余,并判明Symons同余l,d都是α-同余.对于某些拓扑空间X,Y,确定了夹心半群S(X,Y,θ)上的最小(最大)真α-同余.     

序半群序同余的一个注记

序半群S的什么子集可以作为S的同余类是一个重要的问题. 在文[8]中,作者证明了如果序半群S的 理想$C$是$S$的某个同余类, 则$C$是凸的; 而且当$C$是强凸理想时，逆命题成立. 在本文中, 我们给出了序半群同余的一个新的构造，并证明了序半群$S$的理想$B$是$S$的某个同余类的充要条件是$B$是凸的.     

U-纯正半群

型彬半群是正则半群类中纯正半群的一个自然推广．这类半群最先由E1-Qallali和Fountain研究．本文定义了U-纯正半群．这类半群是纯正半群和型W半群二者在U-半富足半群类中的一个共同推广．首先我们确定了U-纯正半群上包含在关系HU中的最小允许同余．借此,证明了半群S为U-纯正半群,当且仅当S可以表示为一个Hall半群和一个V—ample半群的织积．这一结果不仅推广了关于纯正半群结构的著名Hall—Yamada定理,而且推广了E1-Qallali和Fountain建立的型W半群的结构定理．     

弱Clifford形正则半群的半直积和圈积

本文给出两个么半群Ｓ和Ｔ的半直积和圈积为弱Ｃｌｉｆｆｏｒｄ拟正则么半群的充要条件和半直积的结构，同时还讨论了弱Ｃｌｉｆｆｏｒｄ拟正则么半群的最小群同余与半直积的最小群同余之间的关系。     

New concepts for completely regular semigroups

Let 𝒞? denotes the variety of completely regular semigroups considered with the unary operation of inversion. The global study of the lattice of subvarieties of 𝒞? depends heavily on various decompositions. Some of the most fruitful among these are induced by the kernel and the trace relations. In their turn, these relations are induced by the kernel and the trace relations on the lattice of congruences on regular semigroups. These latter admit the concepts of kernel and trace of a congruence. The kernel and the trace relations for congruences were transferred to kernel and trace relations on varieties but the kernel and trace got no analogue for varieties.

We supply here the kernel and the trace of a variety which induce the relations of their namesake. For the local and core relations, we also define the local and core of a variety. All the new concepts are certain subclasses of 𝒞?. In this way, we achieve considerable similarity of the new concepts with those for congruences. We also correct errors in two published papers.     

Using filters to describe congruences and band congruences of semigroups

It is well known that the smallest semilattice congruence can be described via filters. We generalise this result to the smallest left (right) normal band congruences and also to arbitrary semilattice (left normal band, right normal band) congruences, describing them all via filters. To achieve this, we introduce filters relative to arbitrary quasiorders on a semigroup (traditional filters are filters relative to the smallest negative operation-compatible quasiorder). We study congruences which can be described via filters. We show that the lattice of semilattice (left normal band, right normal band) congruences is a homomorphic image of the lattice of negative (right negative, left negative) operation-compatible quasiorders.     

序半群的一类正则同余

设S是有向序半群,本文给出了S上的一类正则同余,称为强序同余的定义及性质.证明了S的强序同余是强正则同余,但反之不成立.同时证明了强序同余格SOC(S)是S的同余格C(S)关于通常集合的交和传递积的V-完备的分配子格.     

Congruences on near-Heyting algebras

A near-Heyting algebra is a join-semilattice with a top element such that every principal upset is a Heyting algebra. We establish a one-to-one correspondence between the lattices of filters and congruences of a near-Heyting algebra. To attain this aim, we first show an embedding from the lattice of filters to the lattice of congruences of a distributive nearlattice. Then, we describe the subdirectly irreducible and simple near-Heyting algebras. Finally, we fully characterize the principal congruences of distributive nearlattices and near-Heyting algebras. We conclude that the varieties of distributive nearlattices and near-Heyting algebras have equationally definable principal congruences.     

Block-separating Congruence Lattices of E-bisimple Semigroups

In this paper,we study block-separating congruences on E-bisimple semigroups. We describe two congruence relations T and W on the lattice of block-separating congruences, where the latter is defined in this paper. We determine the greatest and smallest congruences in T-classes and W-classes.     

Semigroups whose lattices of right congruences are semiatomic

The main theorems presented here are characterizations of a semigroup with a left identity whose lattice of right congruences is semiatomic. These theorems are preceded by a number of results on minimal right congruences.     

A note on the lattice of weak L-valued congruences on the group of prime order

Weak L-valued (fuzzy) congruences on an algebra, where L is a lattice, were induced in [4]. In this note, we give a representation theorem for one subdirect power of L, by means of the lattice of L-valued congruences on any cyclic group of prime order.     

含幺逆半群的半格上的同余格

本文证明了含幺逆半群Sα（α∈Y）的半格的容许同余格同构于半格S上同余格的一个子格。     

On the lattice of weak congruence relations

We consider the setC _w (A) of weak congruences on an algebraA, i.e. of all symmetric and transitive subalgebras ofA ×A. (Some other generalizations of compatible relations were given in [2] and [6]).C _w (A) coincides with the set of all congruences on all subalgebras ofA.We prove here that (^iC _w(A),) is an algebraic lattice having as a sublattice the lattice of all congruences onA, and as a retract the lattice of all its subalgebras. In the second part we give necessary and sufficient conditions (one is the CEP) for modularity as well as for distributivity of the lattice of weak congruences.Presented by H. P. Gumm.     

Irreducible orthomodular lattices which are simple

It is well known that for a chain finite orthomodular lattice, all congruences are factor congruences, so any directly irreducible chain finite orthomodular lattice is simple. In this paper it is shown that the notions of directly irreducible and simple coincide in any variety generated by a set of orthomodular lattices that has a uniform finite upper bound on the lengths of their chains. The prototypical example of such a variety is any variety generated by a set ofn dimensional orthocomplemented projective geometries.Presented by B. Jónsson.Supported by a grant from NSERC.