标题： 自由群的有限逼近 II：Ash、Herwig-Lascar 和 Ribes-Zalesskii 定理——重新审视和加强 显示英文标题

标题： Finite approximation of free groups II: the Theorems of Ash, Herwig-Lascar and Ribes-Zalesskii -- revisited and strengthened

摘要： 定理Ash、Herwig-Lascar和Ribes-Zalesskii之间的关系和相互作用被讨论，并且表明这三个定理在某种意义上是等价的，即每个定理都可以从其他定理中推导出来。还考虑了通过使用第三作者构造提供的群可以得到的这些定理的一些加强形式。 显示英文摘要

摘要： Relations and interactions between the theorems of Ash, Herwig-Lascar and Ribes-Zalesskii are discussed and it is shown that these three theorems are equivalent in the sense that each of them can be derived from each other one. Some strengthening of these theorems that can be obtained by use of the groups provided by the third author's construction are also considered.