置换环的Pierce群

环R的理想P称为Pierce理想,如果R/p是R的Pierce茎.令Pier(R):{P | P是R的Pierce理想}.可证Pier(R)是拓扑空间.若R是幂等元中心的置换环,则Ko(R)≌{f:Pier(R)→Z|f,是连续的).     

具有左中心幂等元的U-富足半群（英文）

本文研究了具有左中心幂等元的U-富足半群的半格分解.利用半格分解,证明了半群S为具有左中心幂等元的U-富足半群,当且仅当S为直积Mα×Λα的强半格,其中Mα是幂幺半群,Λα是右零带.这一结果为具有左中心幂等元的U-富足半群结构的建立奠定了基础.     

幂理想消去的置换环

引进了一类新的部分幂消去的置换环, 得到了置换环幂理想消去的等价刻画, 推广了幂消去的相关结果.     

置换环上的稳定矩阵

本文证明了置换环上的正则稳定矩阵是幂等矩阵和可逆矩阵的积,进一步证明了置换环上的正则稳定矩阵可以对角化。     

具有稳定秩1的置换环

称环R具有稳定秩1,如果对任意的a,b∈R,aR bR=R,则存在Y∈R,使得a by∈U(R).证明了置换环有稳定秩1当且仅当对任意的幂等元e∈R,如果aR b(eR)=R,则存在u,v∈R,使得au b(ev):0且(eR)u (eR)(ev)=eR当且仅当对任意的幂等元e∈R,如果aR b(eR):R,则存在u,t,∈R,使得as b(et)=0当且仅当存在z∈eR,使s=uz,t=vz,从而给出这类置换环新的元素刻画.进一步地,证明了如果R是稳定秩1的置换环,对任意的正则元a∈R,2a总可以表示成两个单位的和.最后对具有降链本原分式的置换环R,证明了对任意的a∈R,2a总可以表示成两个单位的和.     

广义幂比较置换理想

在置换理想上,我们引进了一类广义幂比较;得到了置换理想为广义cu-理想的等价刻画,并推广了置换广义cu-环的相关结果．     

具有中心幂等元的L-弱正则半群

本文定义了具有中心幂等元的(L)-弱正则半群,研究了这类半群的代数结构.利用半群上的右同余(L)+和左同余R+,证明了半群S是一个具有中心幂等元的(L)-弱正则半群,当且仅当S是H-左可消幺半群的强半格.这推广了Clifford半群的相应结果.     

关于赵君喜“R_n~∞中一个幂等元的构造”一文的意见

本文证明了“中一个幂等元的构造”一文中的幂等元Ｑ不是套代数ａｌｇＮ中的算子，因此也不是如该文作者所断言的是中的元。     

Hermite环的扩张（英文）

结合环R的理想I称为Hermite理想,如果I上的任何矩阵都可以对角化.证明了R的正则理想I为Hermite理想当且仅当对任何x∈I~2(x∈~2I),存在y∈col_2(R)(y∈row_2(R))使得xy∈I(yx∈I)是幂等元.进一步证明了任何强可分正则理想是Hermite理想;进而利用一类单位正则性刻画了Hermite正则理想。     

关于赵君喜“R^∞N中一个幂等元的构造”一文的意见

本文证明了“Ｒ＾∞Ｎ中一个幂等元的构造”一文中幂等元Ｑ不是套代数ａｌｇＮ中的算了，因此也不是如该文作者所断言的是Ｒ＾∞Ｎ中的元。     

Homomorphisms of Abelian pomonoids induced by a class of BCI-homomorphisms

In this paper, we investigate further the BCI-G part of a BCI-algebra and give a characterization of quasi-associative BCI-algebras in which every subalgebra is an ideal. Moreover, by using the G-part, we study the homomorphisms of abelian pomonoids induced by a quasi-associative BCI-homomorphism.     

Classes of abelian groups related to sequential convergence

We study classes of abelian groups related to sequential com¬pactness and its generalizations (completeness, coarseness and sequential pre-compactness) in convergence groups. In particular, we describe the algebraic structure of the abelian groups on which every coarse convergence is complete and we prove that: i) every abelian group admits a sequentially precompact convergence; ii) every algebraically compact abelian group admits a sequen¬tially compact convergence.     

Self Extending Rings

A ring R is an IPQ (isomorphic proper quotient)-ring if R ? R/A for every proper ideal A ? R. If every ideal A ? R satisfies: either R ? A or R ? R/A, then R is called an SE (self extending)-ring. It is shown that with one exception, an abelian group G is the additive group of an IPQ-ring if and only if G is the additive group of an SE-ring. The one exception is the infinite cyclic group Z. The zeroring with additive group Z is an SE-ring, but a ring with infinite cyclic additive group is not an IPQ-ring. Since the structure of the additive groups of IPQ-rings is known, the structure of the additive groups of SE-rings is completely determined.     

Two questions on semi-clean group rings

It was proved in [4] that every group ring of a torsion abelian group over a commutative local ring is a semi-clean ring. It was asked in [4] whether every group ring of a torsion abelian group over a commutative clean ring is a semi-clean ring and whether every group ring of a torsion abelian group over a commutative semi-clean ring is a semi-clean ring. In this paper, we give a positive answer to question 1 and a negative answer to question 2.     

On Cellular Covers with Free Kernels

In this paper we show that every cotorsion-free and reduced abelian group of any finite rank (in particular, every free abelian group of finite rank) appears as the kernel of a cellular cover of some cotorsion-free abelian group of rank 2. This situation is the best possible in the sense that cotorsion-free abelian groups of rank 1 do not admit cellular covers with free kernel except for the trivial ones. This work is motivated by an example due to Buckner?CDugas, and recent results obtained by Fuchs?CG?bel, and G?bel?CRodríguez?CStrüngmann.     

On abelian subalgebras and ideals of maximal dimension in supersolvable Lie algebras

In this paper, the main objective is to compare the abelian subalgebras and ideals of maximal dimension for finite-dimensional supersolvable Lie algebras. We characterise the maximal abelian subalgebras of solvable Lie algebras and study solvable Lie algebras containing an abelian subalgebra of codimension 2. Finally, we prove that nilpotent Lie algebras with an abelian subalgebra of codimension 3 contain an abelian ideal with the same dimension, provided that the characteristic of the underlying field is not 2. Throughout the paper, we also give several examples to clarify some results.     

On p-Schur Rings Over Abelian Groups of Order p 3

In the theory of Schur rings, it is known that every Schur ring over a cyclic p-group is Schurian. Recently, Spiga and Wang showed that every p-Schur ring over an elementary abelian p-group of rank 3 is Schurian. In this paper, we prove that every p-Schur ring over an abelian group of order p ³ is Schurian.     

Balanced Hermitian structures on almost abelian Lie algebras

We study balanced Hermitian structures on almost abelian Lie algebras, i.e. on Lie algebras with a codimension-one abelian ideal. In particular, we classify six-dimensional almost abelian Lie algebras which carry a balanced structure. It has been conjectured in [1] that a compact complex manifold admitting both a balanced metric and an SKT metric necessarily has a Kähler metric: we prove this conjecture for compact almost abelian solvmanifolds with left-invariant complex structures. Moreover, we investigate the behaviour of the flow of balanced metrics introduced in [2] and of the anomaly flow [3] on almost abelian Lie groups. In particular, we show that the anomaly flow preserves the balanced condition and that locally conformally Kähler metrics are fixed points.     

Quasi-state rigidity for finite-dimensional Lie algebras

We say that a Lie algebra g is quasi-state rigid if every Ad-invariant continuous Lie quasi-state on it is the directional derivative of a homogeneous quasimorphism. Extending work of Entov and Polterovich, we show that every reductive Lie algebra, as well as the algebras C ⁿ ? u(n), n ≥ 1, are rigid. On the other hand, a Lie algebra which surjects onto the three-dimensional Heisenberg algebra is not rigid. For Lie algebras of dimension ≤ 3 and for solvable Lie algebras which split over a codimension one abelian ideal, we show that this is the only obstruction to rigidity.