Semiring unions of a ring and a half-body

We describe the structure of semirings which are unions of a ring and a half-body.     

半环上同余的刻画

引入半环的完全素理想的概念.利用这一概念,研究了半环的同余,分别给出了半环的子直积分解的若干结果和半环同余的一种刻画.     

几类加法非正则半环

In this paper, we introduce Green＇s .-relations on semirings and define [left, right] adequate semirings to explore additively non-regular semirings. We characterize the semirings which are strong b-lattices of [left, right] skew-halfrings. Also, as further generalization, the semirings are described which are subdirect products of an additively commutative idempotent semiring and a [left, right] skew-halfring. We extend results of constructions of generalized Clifford semirings （given by M. K. Sen, S. K. MaRy, K. P. Shum, 2005） and the semirings which are subdirect products of a distributive lattice and a ring （given by S. Ghosh, 1999） to additively non-regular semirings.     

一类广义正则半环上可除半环同余的等价刻画

研究了一类广义正则半环的理想,利用这类理想,得到了这类半环上同余的几种刻画.     

加法幂等元满足置换等式的纯整半环(英)

本文主要研究加法幂等元满足置换等式的纯整半环．对于这类半环,建立了一个结构定理．     

加法幂等元满足置换等式的纯整半环上的同余

广义逆半群上的同余早已开始研究.在这类半群的性质研究基础上,本文主要给出了加法幂等元满足置换等式的纯整半环上的同余刻画,并且给出了这类半环的同态像的一个结构定理.     

半环上的粗糙集

利用同余关系把粗糙集理论引入到半环里,给出了半环中的一个子集的上,下近似的概念,并研究了其一系列性质;另外我们还讨论了半环中的粗糙理想及性质.     

FP-内射环的一个特征

本文首次利用投射模给出了右ＦＰ-内射环的一个外部特征，即Ｒ为右ＦＰ-内射环当且仅当投射左Ｒ-模的有限生成子模为闭子模。     

满足a+ab=a+b的幂等半环的结构

本文讨论了满足a+ab=a+b的幂等半环的结构,给出这种幂等半环是左零半环的伪强右正规幂等半环,并得出这种幂等半环与环的直积是左环的伪强右正规幂等半环.     

关于FP-内射维数的一个注记

Let R and S be a left coherent ring and a right coherent ring respectively,RωS be a faithfully balanced self-orthogonal bimodule.We give a sufficient condition to show that l.FP-idR（ω） ∞ implies G-dimω（M） ∞,where M ∈ modR.This result generalizes the result by Huang and Tang about the relationship between the FP-injective dimension and the generalized Gorenstein dimension in 2001.In addition,we get that the left orthogonal dimension is equal to the generalized Gorenstein dimension when G-dimω（M） is finite.     

Two concepts of singularity for matrices over semirings

The two common concepts of singularity for matrices over semirings are being studied since the 1970’s and arise from natural generalizations of the determinant and linear dependence. They were introduced in the context of schedule algebras by Gondran and Minoux, who proved later that the concepts discussed are equivalent over any selective invertible semiring. We present an approach that uses a generalization of power series arithmetic and, in particular, allows to derive a short proof for the theorem of Gondran and Minoux. Our main result is a complete concise characterization of semirings over which the two concepts of singularity are equivalent.     

The lattice of idempotent distributive semiring varieties

A solution is given for the word problem for free idempotent distributive semirings. Using this solution the latticeL (ID) of subvarieties of the variety ID of idempotent distributive semirings is determined. It turns out thatL (ID) is isomorphic to the direct product of a four-element lattice and a lattice which is itself a subdirect product of four copies of the latticeL(B) of all band varieties. ThereforeL(ID) is countably infinite and distributive. Every subvariety of ID is finitely based. Project supported by the National Natural Science Foundation of China (Grant No. 19761004) and the Provincial Applied Fundamental Research Foundation of Yunnan (96a001z).     

基于可减的实半环与实素理想

半环R被称为实半环,若对于任意的n∈N,方程x1^2＋…＋xn^2=0在R中只有零解：x1=…=xn=0.为了刻画实半环,引入了实理想和极小素理想的概念,利用同余的方法,得到了可减半环类中实半环的结构定理.     

FP-Injective Complexes

In this article, FP-injective complexes are introduced and studied. We prove that (^⊥??, ??) is a hereditary cotorsion theory if and only if R is a left coherent ring, where ?? denotes the class of all FP-injective complexes of left R-modules. Simultaneously, we study the existence of FP-injective preenvelopes and FP-injective covers.     

A class of inherently nonfinitely based semirings

We give a sufficient condition which ensures that a semiring with an idempotent addition is inherently nonfinitely based. This enables us to provide a number of small and natural examples of nonfinitely based semirings, including semirings of binary relations on a finite set. Supported by Grant No.144011 of the Ministry of Science of the Republic of Serbia.     

Weak Dimension of FP-injective Modules Over Chain Rings

It is proven that the weak dimension of each FP-injective module over a chain ring which is either Archimedean or not semicoherent is less or equal to 2. This implies that the projective dimension of any countably generated FP-injective module over an Archimedean chain ring is less or equal to 3.     

半环半直积的同构定理

半群半直积及封闭性刻划于文[1],为将半直积的研究推广至半环中,本文首先在交换半环与交换半群的直积上定义加法及乘法运算,从而构造了一类半环;半环半直积．并讨论了半环半直积的同构等问题．     

Regularity Criterion for Complete Matrix Semirings

Necessary and sufficient conditions for the regularity of complete matrix semirings over an arbitrary semiring are obtained.     

Gr-凝聚环的分次FP-内射维数

引进了分次FP-内射维数，对Gr-凝聚环的分次FP-内射维数作了刻划，将Stentrom等人的若干工作推广到分次环上．     

Invertible Matrices over Finite Additively Idempotent Semirings

We investigate invertible matrices over finite additively idempotent semirings. The main result provides a criterion for the invertibility of such matrices. We also give a construction of the inverse matrix and a formula for the number of invertible matrices.