Correct formulation of problem $1.D.19$ from Isaacs's Finite Group Theory book












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I think that there is a mispriprint in the formulation of problem $1.D.19$ from Isaacs's book Finite Group Theory (FGT). I give it here




Let $F = F(G)$, where $G$ is an arbitrary finite group, and let $C = C_G(F)$. Show that $G/(G cap F)$ has no non-trivial abelian normal subgroup.




Here $F(G)$ is a Fitting subgroup of $G$. I think that there should be $G/(Fcap C)$ instead of $G/(Gcap F)$ since $G cap F = F$ and in this case the result doesn't depend on $C$. On the other hand if the correct formulation is $G/(F cap C)$, then the result is not valid for example for $G =D_8$. Since in this case $G=F$, $C = Z(G)$ and $G/(Fcap C)$ is isomorpic to $C_2 times C_2$, wich of course has nontrivial abelian normal subgroup.



So, what is the correct formulation of this problem?










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  • 5




    $begingroup$
    It should be $C/(C cap F)$. You could either prove it directly, or deduce it from the result that $C le F$ when $G$ is solvable. I must have a kore recent edition of the book, because mine says $C/(C cap F)$.
    $endgroup$
    – Derek Holt
    Dec 21 '18 at 8:34












  • $begingroup$
    @DerekHolt, thank you very much!
    $endgroup$
    – Mikhail Goltvanitsa
    Dec 21 '18 at 8:36
















1












$begingroup$


I think that there is a mispriprint in the formulation of problem $1.D.19$ from Isaacs's book Finite Group Theory (FGT). I give it here




Let $F = F(G)$, where $G$ is an arbitrary finite group, and let $C = C_G(F)$. Show that $G/(G cap F)$ has no non-trivial abelian normal subgroup.




Here $F(G)$ is a Fitting subgroup of $G$. I think that there should be $G/(Fcap C)$ instead of $G/(Gcap F)$ since $G cap F = F$ and in this case the result doesn't depend on $C$. On the other hand if the correct formulation is $G/(F cap C)$, then the result is not valid for example for $G =D_8$. Since in this case $G=F$, $C = Z(G)$ and $G/(Fcap C)$ is isomorpic to $C_2 times C_2$, wich of course has nontrivial abelian normal subgroup.



So, what is the correct formulation of this problem?










share|cite|improve this question











$endgroup$








  • 5




    $begingroup$
    It should be $C/(C cap F)$. You could either prove it directly, or deduce it from the result that $C le F$ when $G$ is solvable. I must have a kore recent edition of the book, because mine says $C/(C cap F)$.
    $endgroup$
    – Derek Holt
    Dec 21 '18 at 8:34












  • $begingroup$
    @DerekHolt, thank you very much!
    $endgroup$
    – Mikhail Goltvanitsa
    Dec 21 '18 at 8:36














1












1








1





$begingroup$


I think that there is a mispriprint in the formulation of problem $1.D.19$ from Isaacs's book Finite Group Theory (FGT). I give it here




Let $F = F(G)$, where $G$ is an arbitrary finite group, and let $C = C_G(F)$. Show that $G/(G cap F)$ has no non-trivial abelian normal subgroup.




Here $F(G)$ is a Fitting subgroup of $G$. I think that there should be $G/(Fcap C)$ instead of $G/(Gcap F)$ since $G cap F = F$ and in this case the result doesn't depend on $C$. On the other hand if the correct formulation is $G/(F cap C)$, then the result is not valid for example for $G =D_8$. Since in this case $G=F$, $C = Z(G)$ and $G/(Fcap C)$ is isomorpic to $C_2 times C_2$, wich of course has nontrivial abelian normal subgroup.



So, what is the correct formulation of this problem?










share|cite|improve this question











$endgroup$




I think that there is a mispriprint in the formulation of problem $1.D.19$ from Isaacs's book Finite Group Theory (FGT). I give it here




Let $F = F(G)$, where $G$ is an arbitrary finite group, and let $C = C_G(F)$. Show that $G/(G cap F)$ has no non-trivial abelian normal subgroup.




Here $F(G)$ is a Fitting subgroup of $G$. I think that there should be $G/(Fcap C)$ instead of $G/(Gcap F)$ since $G cap F = F$ and in this case the result doesn't depend on $C$. On the other hand if the correct formulation is $G/(F cap C)$, then the result is not valid for example for $G =D_8$. Since in this case $G=F$, $C = Z(G)$ and $G/(Fcap C)$ is isomorpic to $C_2 times C_2$, wich of course has nontrivial abelian normal subgroup.



So, what is the correct formulation of this problem?







group-theory finite-groups






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 21 '18 at 10:19









Nicky Hekster

28.6k63456




28.6k63456










asked Dec 21 '18 at 7:09









Mikhail GoltvanitsaMikhail Goltvanitsa

623414




623414








  • 5




    $begingroup$
    It should be $C/(C cap F)$. You could either prove it directly, or deduce it from the result that $C le F$ when $G$ is solvable. I must have a kore recent edition of the book, because mine says $C/(C cap F)$.
    $endgroup$
    – Derek Holt
    Dec 21 '18 at 8:34












  • $begingroup$
    @DerekHolt, thank you very much!
    $endgroup$
    – Mikhail Goltvanitsa
    Dec 21 '18 at 8:36














  • 5




    $begingroup$
    It should be $C/(C cap F)$. You could either prove it directly, or deduce it from the result that $C le F$ when $G$ is solvable. I must have a kore recent edition of the book, because mine says $C/(C cap F)$.
    $endgroup$
    – Derek Holt
    Dec 21 '18 at 8:34












  • $begingroup$
    @DerekHolt, thank you very much!
    $endgroup$
    – Mikhail Goltvanitsa
    Dec 21 '18 at 8:36








5




5




$begingroup$
It should be $C/(C cap F)$. You could either prove it directly, or deduce it from the result that $C le F$ when $G$ is solvable. I must have a kore recent edition of the book, because mine says $C/(C cap F)$.
$endgroup$
– Derek Holt
Dec 21 '18 at 8:34






$begingroup$
It should be $C/(C cap F)$. You could either prove it directly, or deduce it from the result that $C le F$ when $G$ is solvable. I must have a kore recent edition of the book, because mine says $C/(C cap F)$.
$endgroup$
– Derek Holt
Dec 21 '18 at 8:34














$begingroup$
@DerekHolt, thank you very much!
$endgroup$
– Mikhail Goltvanitsa
Dec 21 '18 at 8:36




$begingroup$
@DerekHolt, thank you very much!
$endgroup$
– Mikhail Goltvanitsa
Dec 21 '18 at 8:36










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