From homogeneous metric spaces to Lie groups

Abstract: We study homogeneous metric spaces, by which we mean connected, locally compact metric spaces whose isometry group acts transitively. After a review of some classical results, we use the Gleason-Iwasawa-Montgomery-Yamabe-Zippin structure theory to show that for all positive $\epsilon$, each such space is $(1,\epsilon)$-quasi-isometric to a connected metric Lie group. Next, we develop the structure theory of Lie groups to show that every homogeneous metric manifold is homeomorphically roughly isometric to a quotient space of a connected amenable Lie group, and roughly isometric to a simply connected solvable metric Lie group. Third, we investigate solvable metric Lie groups in more detail, and expound on and extend work of Gordon and Wilson and of Jablonski on these, showing, for instance, that connected, simply connected solvable Lie groups may be made isometric if and only if they have the same real-shadow. Finally, we extend a result of Kivioja and Le Donne to show that homogeneous metric spaces that admit a metric dilation are all metric Lie groups with an automorphic dilation.