About Sylow subgroup and internal direct product.











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Let $G$ be a finite group and $P$ a Sylow $p$-subgroup of $G$. Let $Q$ be a subgroup of $P$. If $Z(Q)$ is a Sylow $p$-subgroup of $C_G(Q)$, is $C_G(Q)$ a internal direct product of $Z(Q)$ and $O_{p'}(C_G(Q))$?



Notation: $O_{p'}(G)$ is the largest normal subgroup of $G$ of order prime to $p$.



I think the answer is yes, but I can't do it.



It is easy to see that $Z(Q)$ and $O_{p'}(C_G(Q))$ are normal subgroups of $C_G(Q)$, and $Z(Q) cap O_{p'}(C_G(Q)) = 1$.



And I know the following formula :
$$ |AB||A cap B| = |A||B| $$
if $A, B$ are finite subgroups of a group $G$.



How can I prove that $C_G(Q) = Z(Q) O_{p'}(C_G(Q))$?



Thanks!










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    Let $G$ be a finite group and $P$ a Sylow $p$-subgroup of $G$. Let $Q$ be a subgroup of $P$. If $Z(Q)$ is a Sylow $p$-subgroup of $C_G(Q)$, is $C_G(Q)$ a internal direct product of $Z(Q)$ and $O_{p'}(C_G(Q))$?



    Notation: $O_{p'}(G)$ is the largest normal subgroup of $G$ of order prime to $p$.



    I think the answer is yes, but I can't do it.



    It is easy to see that $Z(Q)$ and $O_{p'}(C_G(Q))$ are normal subgroups of $C_G(Q)$, and $Z(Q) cap O_{p'}(C_G(Q)) = 1$.



    And I know the following formula :
    $$ |AB||A cap B| = |A||B| $$
    if $A, B$ are finite subgroups of a group $G$.



    How can I prove that $C_G(Q) = Z(Q) O_{p'}(C_G(Q))$?



    Thanks!










    share|cite|improve this question
























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      up vote
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      down vote

      favorite











      Let $G$ be a finite group and $P$ a Sylow $p$-subgroup of $G$. Let $Q$ be a subgroup of $P$. If $Z(Q)$ is a Sylow $p$-subgroup of $C_G(Q)$, is $C_G(Q)$ a internal direct product of $Z(Q)$ and $O_{p'}(C_G(Q))$?



      Notation: $O_{p'}(G)$ is the largest normal subgroup of $G$ of order prime to $p$.



      I think the answer is yes, but I can't do it.



      It is easy to see that $Z(Q)$ and $O_{p'}(C_G(Q))$ are normal subgroups of $C_G(Q)$, and $Z(Q) cap O_{p'}(C_G(Q)) = 1$.



      And I know the following formula :
      $$ |AB||A cap B| = |A||B| $$
      if $A, B$ are finite subgroups of a group $G$.



      How can I prove that $C_G(Q) = Z(Q) O_{p'}(C_G(Q))$?



      Thanks!










      share|cite|improve this question













      Let $G$ be a finite group and $P$ a Sylow $p$-subgroup of $G$. Let $Q$ be a subgroup of $P$. If $Z(Q)$ is a Sylow $p$-subgroup of $C_G(Q)$, is $C_G(Q)$ a internal direct product of $Z(Q)$ and $O_{p'}(C_G(Q))$?



      Notation: $O_{p'}(G)$ is the largest normal subgroup of $G$ of order prime to $p$.



      I think the answer is yes, but I can't do it.



      It is easy to see that $Z(Q)$ and $O_{p'}(C_G(Q))$ are normal subgroups of $C_G(Q)$, and $Z(Q) cap O_{p'}(C_G(Q)) = 1$.



      And I know the following formula :
      $$ |AB||A cap B| = |A||B| $$
      if $A, B$ are finite subgroups of a group $G$.



      How can I prove that $C_G(Q) = Z(Q) O_{p'}(C_G(Q))$?



      Thanks!







      sylow-theory direct-product






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      asked Nov 15 at 17:11









      Snowbaby

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