非负矩阵的［0-单］单子半群

本文研究非负矩阵［0-单］单子半群,特别证明M_n(S)的［0-单］单子半群是完全［0-单］单的,其中S是强理想除0外每个元素都大于或等于1.最后举例说明非负矩阵 半群是一类有趣的半群.     

完全■-单半群

完全■-单半群是完全单半群和完全■~*-单半群在U-半富足半群类中的一个自然推广.本文证明了半群S是完全■-单半群,当且仅当S同构于幺半群T上的正规Rees矩阵半群■(T;I,A;P).这一结果不仅推广了完全单半群的著名Rees定理,而且推广了任学明和岑嘉评在2004年建立的完全■~*-单半群的一个结构定理.     

可分解半群的Morita等价

设S,R是可分解半群.记US-FAct={sM∈S-Act|SM=M且SHoms(S,M)≌M],给出了范畴US-FAct与UR-FAct等价的刻划;S分别强Morita等价于一个夹层半群、局部单位半群、幺半群和群的条件;S是完全单半群当且仅当S强Morita等价于一个群且对任何指标集I,S SHoms(S,i∈I S)→i∈I S,s t·f→(st)f,是同构.     

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.     

半群的广义Clifford定理

令U为U-半富足半群的投射元集合.每个H-类含投射元的U-富足半群称为U-超富足半群.这种半群是完全正则半群和超富足半群在U-半富足半群类中的一个共同推广.1941年,Clifford证明了半群S为完全正则半群,当且仅当S为完全单半群的半格.40多年后,Fountain将这一结果推广到了超富足半群上.本文关于U-超富足半群得到了广义Clifford定理.这一结果分别以Clifford和Fountain的上述结果为其推论.     

完全J~(e)-单半群（英文）

半群S称为完全J~(e)-单半群,如果S同构于某个左消幺半群上的Rees矩阵半群.本文得到了这类半群的若干特征和簇性质.     

L*-逆半群的结构

定义了L*-逆半群,并引入了半群左圈积的概念.证明了半群S是一个L*-逆半群,当且仅当S是一个型A半群Γ和一个左正则带B连同结构映射ψ的左圈积B( )ψΓ.这一结果的一个直接推论是关于左逆半群结构的著名Yamada定理.利用半群的左圈积,给出了一个非平凡的L*-逆半群的例子.     

0-恰当半群

引入了0-恰当半群的概念,它是一种特殊的逆半群.给出了0-恰当半群的等价刻划.讨论具有幂等半格的右0-恰当半群上含于(够)0的最大同余关系μL和具有幂等半格的0-恰当半群上含于(形)0的最大同余关系μ.证明如果S是一个具有幂等半格E的右0-A型半群,则S/μL≌E当且仅当S是一个S0左逆的左消含幺半群的强半格.进一步证明了,如果S是一个具有幂等半格E的0-恰当半群,则S/μ≌E当且仅当S是一个S0逆的消去含幺半群的强半格.     

良B-拟Ehresmann半群

设S是一个半群,B是S的一个子带.如果S是一个满足同余条件的B-半富足半群,且对所有的a,b∈S都有aB（a＊）B（b＋）b B（（ab）＋）abB（（ab）＊）,就称S为一个良B-拟Ehresmann半群.本文给出了良B-拟Ehresmann半群的整体表示和标准表示,并作为特殊情形得到了良拟适当半群的结构刻画.     

正规密码H~#-富足半群的结构

证明了H~#-富足半群S是正规密码H~#-富足半群当且仅当它是完全J~#-单半群的强半格.该结果也是正规密码超富足半群和正规密码群并半群分别在超富足半群和完全正则半群上的相应结构定理的推广.     

Homomorphisms of implicative semigroups

Implicative semigroups and Brouwerian semigroups were studied by W. C. Nemitz and T. S. Blyth, respectively. In this paper, following the ideas of Nemitz and Blyth, we introduce the notion of negatively partially ordered implicative semigroups and studied the homomorphisms between these semigroups. Some results of Nemitz on implicative semilattices are generalized and amplified to implicative semigroups. Research is partially supported by CUHK small Project grant 220.600.080.     

Fuzzy Ordered Filters in Implicative Semigroups

Animplicativesemilatticeisanalgebraicsystemhavingasmodelslogicalsystemsequippedwithimplicationandconjunction,butnotpossessingadisjunction.ImplicativesemilatticeswerestudiedbyW.C.Nemitz[5].In[2],T.S.BlythgeneralizedsomeresultsofW.C.Nemitz[5]byintroducingthenotionofaBrouweriansemigroup.FollowingtheideasofNemitzandBlyth,M.W.ChanandK.P.Shum[3]introducedthenotionofnegativelypartiallyorderedimplicativesemigroupsandgeneralizedsomeresultofNemitzonimplicativesemilatticestoim-plicativesemigroups…     

On Ordered Semigroups Which are Semilattices of Simple and Regular Semigroups

We characterize the ordered semigroups which are decomposable into simple and regular components. We prove that each ordered semigroup which is both regular and intra-regular is decomposable into simple and regular semigroups, and the converse statement also holds. We also prove that an ordered semigroup S is both regular and intra-regular if and only if every bi-ideal of S is an intra-regular (resp. semisimple) subsemigroup of S. An ordered semigroup S is both regular and intra-regular if and only if the left (resp. right) ideals of S are right (resp. left) quasi-regular subsemigroups of S. We characterize the chains of simple and regular semigroups, and we prove that S is a complete semilattice of simple and regular semigroups if and only if S is a semilattice of simple and regular semigroups. While a semigroup which is both π-regular and intra-regular is a semilattice of simple and regular semigroups, this does not hold in ordered semigroups, in general.     

On ordered filters of implicative semigroups

In this paper, we first study how to generate an ordered filter by a set. Secondly, we discuss prime ordered filters in commutative implicative semigroups, and establish prime and irreducible decompositions Supported by the Basic Science Research Institute Program, Ministry of Education, 1994, Project No. BSRI-94-1406.     

The Semigroup Characterizations of Positive Implicative BCK—algebras

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＢｙａＢＣＩ－ａｌｇｅｂｒａｗｅｍｅａｎａｎａｌｇｅｂｒａ（Ｘ，，０）ｏｆｔｙｐｅ（２，０）ｗｉｔｈｔｈｅｆｏｌｌｏｗｉｎｇｃｏｎｄｉ－ｔｉｏｎｓ：（１）（（ｘｙ）（ｘｚ））（ｚｙ）＝０；（２）（ｘ（ｘｙ））ｙ＝０；（３）ｘｘ＝０；（４）ｘｙ＝ｙｘ＝０ｉｍｐｌｉｅｓｘ＝ｙ．ＩｆａＢＣＩ－ａｌｇｅｂｒａ（Ｘ，，０）ｓａｔｉｓｆｉｅｓ（５）０ｘ＝０．ｔｈｅｎｉｔｉｓｃａｌｌｅｄａＢＣＫ－ａｌｇｅｂｒａ．ＩｎａＢＣＩ－ａｌｇｅｂｒａ，ｔｈｅｆ…     

On the Adjoint Monoids of Implicative BCK-algebras

We give some semigroup characterizations for implicative BCK-algebras, and prove that the adjoint semigroups of implicative BCK-algebras are residualed semigroups.AMS Subject Classification (2000): 03G25, 06F35     

关于强可逆半准素序半群

把由G．Thierrin和A．Spoletini-Cherubini等人定义并研究的强可逆半群以及由S．Bogdanovic研究的半准素半群分别推广为强可逆序半群和半准素序半群．分别给出了半准素序半群和强可逆序半群类中的半准素序半群的刻划，还给出了其所有理想是素理想的强可逆序半群的刻划．     

Implicative commutative semigroups are equivalent to a class of BCK algebras

Chan and Shum [2] introduced the notion of implicative semigroups and obtained some of its important properties. BCK algebras with condition (S) were introduced by Iséki [4] and extensively investigated by several authors. In this note, we prove that implicative commutative semigroups are equivalent to BCK algebras with condition (S), that is, given an algebra <S;≤,·,*,1> of type (2,2,0), define ⊗ by stipulatingx⊗y=y*x and ≺ by puttingx≺y if and only ify≤x, then <S≤,·,*,1> is an implicative commutative semigroup if and only if <S;≺,·,⊗, 1> is a BCK algebra with condition (S); a nonempty subsetF ofS is an ordered filter of <S;≤,·,*, 1> if and only ifF is an ideal of <S;≺,·, ⊗, 1>. The author would like to thank the referee for his valuable comments which helped in the modification of this paper.     

关于序半群的模糊拟理想

In this paper,fuzzy quasi-ideals of ordered semigroups are characterized by the properties of their level subsets.Furthermore,we introduce the notion of completely semiprime fuzzy quasi-ideals of ordered semigroups and characterize strongly regular ordered semigroups in terms of completely semiprime fuzzy quasi-ideals.Finally,we investigate the characterizations and decompositions of left and right simple ordered semigroups by means of fuzzy quasi-ideals.