论文标题
亚组的代数和无上下文子集
Algebraic and context-free subsets of subgroups
论文作者
论文摘要
我们研究了G组G组的代数和无上下文基础的结构与有限指数亚组H之间的关系。使用这些结果，我们证明，Berstel和Sakarovitch先前在理性的子集中和赫尔布斯特（HerbSt）的范围内，在代数范围内，far的属性是forts-forect for contect-firt and covtemets if and grout if the if nift and if the firception，如果是herbst，则是If and offect of the offect of the offect offect offect offect-firt。我们还展示了有关代数子集这一属性的Herbst问题的反例。
We study the relation between the structure of algebraic and context-free subsets of a group G and that of a finite index subgroup H. Using these results, we prove that a kind of Fatou property, previously studied by Berstel and Sakarovitch in the context of rational subsets and by Herbst in the context of algebraic subsets, holds for context-free subsets if and only if the group is virtually free. We also exhibit a counterexample to a question of Herbst concerning this property for algebraic subsets.
