Chabauty topology
In mathematics, the Chabauty topology is a certain topological structure introduced in 1950 by Claude Chabauty, on the set of all closed subgroups of a locally compact group G. It is closely related to the Fell topology on the set of all closed subsets of G and to the Hausdorff distance. Intuitively, two closed subgroups of G are close in the Chabauty topology if, within any compact subset of G, every point of one subgroup is close to some point of the other, and vice versa.