设S为有单位元1的半群,引入并讨论了自由半群作用的Galois盖和斜半群作用范畴的概念及性质,证明了自由半群作用范畴的商范畴与斜半群作用范畴是等价的.
Let S be a semigroup with identity 1.Introduces the definition of Galois covering of free S-category and skew category with semigroup action,discusses their properties;proves that quotient category of free S-category is equivalent to the skew category with semigroup action.