Characterization of non solvable groups in terms of normal series.












1












$begingroup$


I have encountered the following statement which I cannot prove:




A finite group $G$ is not solvable if and only if there is a NORMAL series with



$$ 1lhd H lhd N lhd G $$



such that $N/H$ is a nonabelian simple group or product of isomorphic nonabelian simple groups.




I guess by a normal series is meant the usual, that any term of the series is normal in the whole group $G$.



Any help would be greatly appreciated.










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$endgroup$












  • $begingroup$
    $H/N$ should be $N/H$. I'm not allowed to do this as an edit as it involves too few characters.
    $endgroup$
    – David Towers
    Jun 6 '17 at 6:54










  • $begingroup$
    Which direction of the proof do you have problems with? In either case, since $G$ is finite, you can use the method of infinite descent (i.e. assume that $G$ is a counterexample of minimal order).
    $endgroup$
    – jpvee
    Jun 8 '17 at 8:46
















1












$begingroup$


I have encountered the following statement which I cannot prove:




A finite group $G$ is not solvable if and only if there is a NORMAL series with



$$ 1lhd H lhd N lhd G $$



such that $N/H$ is a nonabelian simple group or product of isomorphic nonabelian simple groups.




I guess by a normal series is meant the usual, that any term of the series is normal in the whole group $G$.



Any help would be greatly appreciated.










share|cite|improve this question











$endgroup$












  • $begingroup$
    $H/N$ should be $N/H$. I'm not allowed to do this as an edit as it involves too few characters.
    $endgroup$
    – David Towers
    Jun 6 '17 at 6:54










  • $begingroup$
    Which direction of the proof do you have problems with? In either case, since $G$ is finite, you can use the method of infinite descent (i.e. assume that $G$ is a counterexample of minimal order).
    $endgroup$
    – jpvee
    Jun 8 '17 at 8:46














1












1








1





$begingroup$


I have encountered the following statement which I cannot prove:




A finite group $G$ is not solvable if and only if there is a NORMAL series with



$$ 1lhd H lhd N lhd G $$



such that $N/H$ is a nonabelian simple group or product of isomorphic nonabelian simple groups.




I guess by a normal series is meant the usual, that any term of the series is normal in the whole group $G$.



Any help would be greatly appreciated.










share|cite|improve this question











$endgroup$




I have encountered the following statement which I cannot prove:




A finite group $G$ is not solvable if and only if there is a NORMAL series with



$$ 1lhd H lhd N lhd G $$



such that $N/H$ is a nonabelian simple group or product of isomorphic nonabelian simple groups.




I guess by a normal series is meant the usual, that any term of the series is normal in the whole group $G$.



Any help would be greatly appreciated.







finite-groups normal-subgroups solvable-groups






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 22 '18 at 5:12









Shaun

9,241113684




9,241113684










asked Jun 5 '17 at 16:09









muser17muser17

192




192












  • $begingroup$
    $H/N$ should be $N/H$. I'm not allowed to do this as an edit as it involves too few characters.
    $endgroup$
    – David Towers
    Jun 6 '17 at 6:54










  • $begingroup$
    Which direction of the proof do you have problems with? In either case, since $G$ is finite, you can use the method of infinite descent (i.e. assume that $G$ is a counterexample of minimal order).
    $endgroup$
    – jpvee
    Jun 8 '17 at 8:46


















  • $begingroup$
    $H/N$ should be $N/H$. I'm not allowed to do this as an edit as it involves too few characters.
    $endgroup$
    – David Towers
    Jun 6 '17 at 6:54










  • $begingroup$
    Which direction of the proof do you have problems with? In either case, since $G$ is finite, you can use the method of infinite descent (i.e. assume that $G$ is a counterexample of minimal order).
    $endgroup$
    – jpvee
    Jun 8 '17 at 8:46
















$begingroup$
$H/N$ should be $N/H$. I'm not allowed to do this as an edit as it involves too few characters.
$endgroup$
– David Towers
Jun 6 '17 at 6:54




$begingroup$
$H/N$ should be $N/H$. I'm not allowed to do this as an edit as it involves too few characters.
$endgroup$
– David Towers
Jun 6 '17 at 6:54












$begingroup$
Which direction of the proof do you have problems with? In either case, since $G$ is finite, you can use the method of infinite descent (i.e. assume that $G$ is a counterexample of minimal order).
$endgroup$
– jpvee
Jun 8 '17 at 8:46




$begingroup$
Which direction of the proof do you have problems with? In either case, since $G$ is finite, you can use the method of infinite descent (i.e. assume that $G$ is a counterexample of minimal order).
$endgroup$
– jpvee
Jun 8 '17 at 8:46










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