Consider a quotient group $G/H$. If there is a section that is a subgroup of $G$ (I mean a transversal that is also a group), must the group be necessarily a semidirect (including direct) product?
Sections of quotient groups and semidirect products
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abstract-algebra
group-theory
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0I'm not exactly sure what the question is but I'm guessing the answer has something to do with the splitting lemma. See [here](http://mathworld.wolfram.com/GroupExtension.html) for some information. – 2012-02-28
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7If there is a transversal $T$ of $H$ in $G$ that is a subgroup of $G$, then $T$ is a complement of $H$ in $G$, so the extension is split, and is isomorphic/equal to a semidirect product of $H$ by $T$. – 2012-02-28
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1note TH = G and $T\cap H = \{e\}$ and H is normal. one can define the homomorphism from T to Aut(H) explicitly by conjugating h in H by t in T. – 2012-03-04