正则半群的拟C同余

本文给出拟C半群的一个等价条件,研究了正则半群的拟C同余,用同余的核和超迹描述拟C同余.     

关于不定方程■（x＋i）~n＝（x＋h＋1）~n的解

证明了：当１００＜ｎ≤２００时，不定方程无正整数解．     

关于Dn中半格置换相似的一个注记

文章[4]给出了Dn中的半格置换相似于Tn中的某个半格的充要条件.对于这个充要条件,本文在[5]的基础上给出另一个更简洁的等价描述.     

Semilattice transversals of regular bands I

Every regular band can be isomorphically embedded into a regular band which has a semilattice transversal. The latter constitute the variety of regular split bands, whose subvariety lattice is isomorphic to the lattice of regular band varieties.     

双重K_1_1_代数

本文介绍一个双重Ｋ１．１－代数（Ｌ;－,＋）的概念,视（Ｌ;－）及其对偶（Ｌｄ;＋）为其Ｋ１．１－代数,且赋予一元运算ｘ－ｘ＾－和ｘ－ｘ＾＋某种相关的条件,我们证明,对一个次直不可约的双重Ｋ１．１－代数（Ｌ;－,＋）有绝对值Ｌ≤３２,且Ｌ绝对值≠３１、２９。     

半环的星同态

本文引入了半环的星元素、星理想、星同余、星同态等概念,得到了半环的星同态的一些重要性质.     

A “Generalized Trace Formula” for Bell numbers

The nth Bell number B_n is the number of ways to partition a set of n elements into nonempty subsets. We generalize the “trace formula” of Barsky and Benzaghou [1], which asserts that for an odd prime p and an appropriate constant τ_p, the relation B_n=-Tr(^n-1-τ_p)B_τp holds in , where is a root of and is the trace form. We deduce some new interesting congruences for the Bell numbers, generalizing miscellaneous well-known results including those of Radoux [4].     

A class of congruences in partial Abelian semigroups

In this paper, by basing on the special morphism of Habil, we introduce and study a class of congruences in partial Abelian semigroups and obtain some interesting properties. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

On the definition of a Lachlan semilattice

We study the algorithmic properties of the semilattices introduced in 1972 by Lachlan in his work on recursively enumerable m-degrees, the so-called Lachlan semilattices. We show that in Lachlan’s definition the effectivity condition on the meet can be omitted in the sequence determining such a semilattice.     

On Left Regular Ordered Semigroups

The main result of the paper is a decomposition theorem of the left regular ordered semigroups into left regular and left simple semigroups.