Groups associated with minimal flows

Let S be topological semigroup, we consider an appropriate semigroup compactification Ŝ of S. In this paper we study the connection between subgroups of a maximal group in a minimal left ideal of Ŝ, which arise as equivalence classes of some closed left congruence, and the minimal ow characterized by the left congruence. A particular topology is defined on a maximal group and it is shown that a closed subgroup under this topology is precisely the intersection of an equivalence class with the maximal group for some left congruence on Ŝ. © Mathematical Institute, Academy of Sciences of Czech Republic 2005