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Suppose $G_1$ and $G_2$ are Lie groups with isomorphic Lie algebras. Then from standard Lie theory we know that there is a simply connected Lie group $G$ such that $G/H_i = G_i$ where $H_i$ is a discrete subgroup of the center of $G$. I am curious if there is a nice condition on $H_1,H_2$ and how they sit in $G$ that implies $G_1$ and $G_2$ are isomorphic.

More generally I guess, when is $G/H = G/K$ for a general group $G$ and normal subgroups $H$ and $K$ (maybe having $H$ and $K$ be in the center makes things easier?).

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The condition is that there is an automorphism $f : G \to G$ such that $f(H_1)=H_2$. The idea is if $h : G_1 \to G_2$ is an isomorphism, lift it to a map $G \to G$. –  Ryan Budney Nov 5 '10 at 1:45
Thanks that's simple enough! –  Eric O. Korman Nov 9 '10 at 19:08
@Ryan: I know this is old, but I see no reason why you shouldn't post your comment as an answer. –  mixedmath May 9 '12 at 5:01

1 Answer 1

Copied RB's comment as an answer:

The condition is that there is an automorphism f:G→G such that f(H1)=H2. The idea is if h:G1→G2 is an isomorphism, lift it to a map G→G.

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