Complex sentence: Note that the elements of Out ("G ") are cosets of automorphisms of"G", and not themselves automorphisms; this is an instance of the fact that quotients of groups are not in general subgroups.
Split into simpler sentences: Note that the elements of Out ("G ") are cosets of automorphisms of"G", and not themselves automorphisms. This is an instance of the fact that quotients of groups are not in general subgroups.