有局部单位半群上循环系的投射覆盖  

On Projective Covers of Cyclic Acts over Semigroups with Local Units

作　　者：杨文杰 梁星亮[1,2] 卫柏岩 YANG Wen-jie;LIANG Xing-liang;WEI Bai-yan(School of Mathematics and Data Science,Shaanxi University of Science and Technology,Xi'an 710021,China;School of Mathematics,Northwest University,Xi'an 710127,China)

机构地区：[1]陕西科技大学数学与数据科学学院,陕西西安710021 [2]西北大学数学学院,陕西西安710127

出　　处：《数学的实践与认识》2022年第12期212-216,共5页Mathematics in Practice and Theory

基　　金：国家自然科学基金(12001345);中国博士后科学基金面上项目(2020M673618XB);陕西省教育厅研究项目(18JK0087)。

摘　　要：设S是有局部单位半群.借助S-系同余给出了投射循环酉S-系的新刻画,并刻画了循环酉S-系有投射覆盖的有局部单位半群的特征,推广了幺半群上投射覆盖的相关结果.Let S be semigroups with local units.In the paper,some new characterizations of projective and unitary cyclic S-acts are given by using S-act congruences,semigroups S with local units over which a cyclic S-act has a projective cover are characterized.Furthermore,many known results about projective covers of cyclic acts over monoids are generalized.

关 键 词：S-系 有局部单位半群 同余 投射覆盖 

分 类 号：O152.7[理学—数学]