Relative Regular Objects in Categories

We define the concept of a regular object with respect to another object in an arbitrary category. We present basic properties of regular objects and we study this concept in the special cases of abelian categories and locally finitely generated Grothendieck categories. Applications are given for categories of comodules over a coalgebra and for categories of graded modules, and a link to the theory of generalized inverses of matrices is presented. Some of the techniques we use are new, since dealing with arbitrary categories allows us to pass to the dual category.      

PreT 2 Objects in Topological Categories

In previous papers, two notions of pre-Hausdorff (PreT ₂) objects in a topological category were introduced and compared. The main objective of this paper is to show that the full subcategory of PreT ₂ objects is a topological category and all of T ₀, T ₁, and T ₂ objects in this topological category are equivalent. Furthermore, the characterizations of pre-Hausdorff objects in the categories of filter convergence spaces, (constant) local filter convergence spaces, and (constant) stack convergence spaces are given and as a consequence, it is shown that these categories are homotopically trivial.     

Coreflections Versus Regular Epimorphisms in Categories of Topological Spaces

Let be an epireflective subcategory of the category Top of topological spaces which is not contained in the category of indiscrete spaces (e.g. Top, the category of Hausdorff spaces, the category of Tychonoff spaces) and be a coreflective subcategory of . In this paper we prove that the coreflector preserves regular epimorphisms if and only if or is contained in the category of discrete spaces.     

正则关系与完全正则空间

借助于关系的某些代数性质刻画拓扑空间的完全正则性,证明了拓扑空间是完全正则的当且仅当其闭集与开集之间存在满足一定简单条件的正则关系,有限正则关系或广义有限正则关系.     

Completely Regular Semigroup Varieties Whose Free Objects Have Weakly Permutable Fully Invariant Congruences

We prove that a variety of completely regular semigroups has the property from the title if and only if it consists of either completely simple semigroups or semilattices of groups.     

Automorphic Objects in Categories

Siberian Mathematical Journal -     

完全单半群及完全正则半群的逆断面

指出完全单半群Ｓ的任何一个Ｆ－类是逆断面,且为Ｑ－逆断面,而Ｓ的任何一个逆断面必是一个Ｆ－类,因而所有逆断面同构。并且给出完全正则半群的逆断面存在的充要条件。     

Locally Completely Regular Epigroups

The object of the article is to characterize epigroups which are locally completely regular. Some subclasses of such epigroups are also described.     

Abel正则球与完全正则半群

本文分别讨论了关于结合环和半群的二个定理，并且由结合环的这二个定理推出了如下准则：结合环Ｒ是Ａｂｅｌ正则的，当且仅当Ｒ的每个拟理想是正则环．     

Realizations of Topological Categories

There are functor-preordering-structured categories S(F,P), defined by the Prague School, in which every concrete category over a concretizable basecategory is realizable. Over nice basecategories there are realizations of all topological categories in some topological S(F,L). This gives rise for a new characterization of those concrete categories having a topological hull.     

拟正则半群上的完全正则同余

拟正则半群上的两个完全正则同余相等当且仅当它们的核正规系相同。更进一步地,我们还可建立一个从一个拟正半群上的全体完全正则同余的集合到这个半群的所有完全正则核正规系的集合上的双射。     

Ideals and Clots in Pointed Regular Categories

We clarify the relationship between ideals, clots, and normal subobjects in a pointed regular category with finite coproducts. Partially supported by South African NRF Research partially supported by the Hungarian National Foundation for Scientific Research grant no. K61007.     

关于Fuzzy完全正则半群

本文先引入Ｆｕｚｚｙ左（Ｆｕｚｚｙ右）正则半群的概念，进而讨论Ｆｕｚｚｙ左（Ｆｕｚｚｙ右）正则半群以及Ｆｕｚｚｙ完全正则半群中Ｆｕｚｚｙ理想的一些代数性质。     

Globals of Completely Regular Monoids

An element of a semigroup S is called irreducible if it cannot be expressed as a product of two elements in S both distinct from itself. In this paper we show that the class C of all completely regular...     

Rickart and Dual Rickart Objects in Abelian Categories

We introduce and study relative Rickart objects and dual relative Rickart objects in abelian categories. We show how our theory may be employed in order to study relative regular objects and (dual) relative Baer objects in abelian categories. We also give applications to module and comodule categories.     

Completely Regular Designs of Strength One

We study a class of highly regular t-designs. These are the subsets of vertices of the Johnson graph which are completely regular in the sense of Delsarte [2]. In [9], Meyerowitz classified the completely regular designs having strength zero. In this paper, we determine the completely regular designs having strength one and minimum distance at least two. The approach taken here utilizes the incidence matrix of (t+1)-sets versus k-sets and is related to the representation theory of distance-regular graphs [1, 5].     

在具有终对象的范畴内的正合列

本文对于具有终对象的范畴定义了四个一般正合列．在Ａｂｅｌ范畴同调代数里，对于具有零对象的任何范畴四个一般正合列与通常的正合列相同