Published online by Cambridge University Press: 21 December 2021
For a locally compact metrisable group G, we study the action of  ${\rm Aut}(G)$ on
${\rm Aut}(G)$ on  ${\rm Sub}_G$, the set of closed subgroups of G endowed with the Chabauty topology. Given an automorphism T of G, we relate the distality of the T-action on
${\rm Sub}_G$, the set of closed subgroups of G endowed with the Chabauty topology. Given an automorphism T of G, we relate the distality of the T-action on  ${\rm Sub}_G$ with that of the T-action on G under a certain condition. If G is a connected Lie group, we characterise the distality of the T-action on
${\rm Sub}_G$ with that of the T-action on G under a certain condition. If G is a connected Lie group, we characterise the distality of the T-action on  ${\rm Sub}_G$ in terms of compactness of the closed subgroup generated by T in
${\rm Sub}_G$ in terms of compactness of the closed subgroup generated by T in  ${\rm Aut}(G)$ under certain conditions on the center of G or on T as follows: G has no compact central subgroup of positive dimension or T is unipotent or T is contained in the connected component of the identity in
${\rm Aut}(G)$ under certain conditions on the center of G or on T as follows: G has no compact central subgroup of positive dimension or T is unipotent or T is contained in the connected component of the identity in  ${\rm Aut}(G)$. Moreover, we also show that a connected Lie group G acts distally on
${\rm Aut}(G)$. Moreover, we also show that a connected Lie group G acts distally on  ${\rm Sub}_G$ if and only if G is either compact or it is isomorphic to a direct product of a compact group and a vector group. All the results on the Lie groups mentioned above hold for the action on
${\rm Sub}_G$ if and only if G is either compact or it is isomorphic to a direct product of a compact group and a vector group. All the results on the Lie groups mentioned above hold for the action on  ${\rm Sub}^a_G$, a subset of
${\rm Sub}^a_G$, a subset of  ${\rm Sub}_G$ consisting of closed abelian subgroups of G.
${\rm Sub}_G$ consisting of closed abelian subgroups of G.
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