A finite group is isomorphic to the direct product of two normal subsets with trivial intersectionUnderstanding the internal direct product of a group.Let N1 and N2 are normal subgroups in the finite group G. Is it true that if N1≃N1 then G∖N1≃G∖N2.?Normal subgroups of direct productProve that $G$ is the internal direct product of their normal subgroups $N_1,N_2,ldots ,N_n$?If $H$ is a normal subgroup of a finite group $G$ and $|H|=p^k$ for some prime $p$. show that $H$ is contained in every sylow $p$ subgroup of $G$Proving that product of two quotients = a certain quotient groupFaithful irreducible character of a group with exactly two minimal normal subgroupsFrattini subgroup of a finite elementary abelian $p$-group is trivialIntersection of Frattini subgroup and center of a finite $p$-groupMinimal normal, maximal and isomorphic

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A finite group is isomorphic to the direct product of two normal subsets with trivial intersection


Understanding the internal direct product of a group.Let N1 and N2 are normal subgroups in the finite group G. Is it true that if N1≃N1 then G∖N1≃G∖N2.?Normal subgroups of direct productProve that $G$ is the internal direct product of their normal subgroups $N_1,N_2,ldots ,N_n$?If $H$ is a normal subgroup of a finite group $G$ and $|H|=p^k$ for some prime $p$. show that $H$ is contained in every sylow $p$ subgroup of $G$Proving that product of two quotients = a certain quotient groupFaithful irreducible character of a group with exactly two minimal normal subgroupsFrattini subgroup of a finite elementary abelian $p$-group is trivialIntersection of Frattini subgroup and center of a finite $p$-groupMinimal normal, maximal and isomorphic













3












$begingroup$


I have to show the following:



Let $G$ be a finite group and $N_1 , N_2$ normal in $G$.
Then $Gcong N_1times N_2$ if and only if $N_1cap N_2 = e$.



I have no idea on either direction, so I would be grateful for any little hint!



Thank you!










share|cite|improve this question









$endgroup$
















    3












    $begingroup$


    I have to show the following:



    Let $G$ be a finite group and $N_1 , N_2$ normal in $G$.
    Then $Gcong N_1times N_2$ if and only if $N_1cap N_2 = e$.



    I have no idea on either direction, so I would be grateful for any little hint!



    Thank you!










    share|cite|improve this question









    $endgroup$














      3












      3








      3


      0



      $begingroup$


      I have to show the following:



      Let $G$ be a finite group and $N_1 , N_2$ normal in $G$.
      Then $Gcong N_1times N_2$ if and only if $N_1cap N_2 = e$.



      I have no idea on either direction, so I would be grateful for any little hint!



      Thank you!










      share|cite|improve this question









      $endgroup$




      I have to show the following:



      Let $G$ be a finite group and $N_1 , N_2$ normal in $G$.
      Then $Gcong N_1times N_2$ if and only if $N_1cap N_2 = e$.



      I have no idea on either direction, so I would be grateful for any little hint!



      Thank you!







      group-theory finite-groups






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked May 4 at 9:35









      TwoStonesTwoStones

      676




      676




















          1 Answer
          1






          active

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          8












          $begingroup$

          This is not true unless $N_1,N_2$ generates $G$, in this case let $p_i:Grightarrow G/N_i$ the quotient map, show that $p_1$ iduces an isomorphism $N_2rightarrow G/N_1$. Consider $f:Grightarrow N_1times N_2$ defined $f(x)=(p_1(x),p_2(x))$ show that it is an isomorphism.






          share|cite|improve this answer









          $endgroup$












          • $begingroup$
            Thank you very much!
            $endgroup$
            – TwoStones
            May 4 at 10:17











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          active

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          active

          oldest

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          8












          $begingroup$

          This is not true unless $N_1,N_2$ generates $G$, in this case let $p_i:Grightarrow G/N_i$ the quotient map, show that $p_1$ iduces an isomorphism $N_2rightarrow G/N_1$. Consider $f:Grightarrow N_1times N_2$ defined $f(x)=(p_1(x),p_2(x))$ show that it is an isomorphism.






          share|cite|improve this answer









          $endgroup$












          • $begingroup$
            Thank you very much!
            $endgroup$
            – TwoStones
            May 4 at 10:17















          8












          $begingroup$

          This is not true unless $N_1,N_2$ generates $G$, in this case let $p_i:Grightarrow G/N_i$ the quotient map, show that $p_1$ iduces an isomorphism $N_2rightarrow G/N_1$. Consider $f:Grightarrow N_1times N_2$ defined $f(x)=(p_1(x),p_2(x))$ show that it is an isomorphism.






          share|cite|improve this answer









          $endgroup$












          • $begingroup$
            Thank you very much!
            $endgroup$
            – TwoStones
            May 4 at 10:17













          8












          8








          8





          $begingroup$

          This is not true unless $N_1,N_2$ generates $G$, in this case let $p_i:Grightarrow G/N_i$ the quotient map, show that $p_1$ iduces an isomorphism $N_2rightarrow G/N_1$. Consider $f:Grightarrow N_1times N_2$ defined $f(x)=(p_1(x),p_2(x))$ show that it is an isomorphism.






          share|cite|improve this answer









          $endgroup$



          This is not true unless $N_1,N_2$ generates $G$, in this case let $p_i:Grightarrow G/N_i$ the quotient map, show that $p_1$ iduces an isomorphism $N_2rightarrow G/N_1$. Consider $f:Grightarrow N_1times N_2$ defined $f(x)=(p_1(x),p_2(x))$ show that it is an isomorphism.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered May 4 at 9:49









          Tsemo AristideTsemo Aristide

          62k11447




          62k11447











          • $begingroup$
            Thank you very much!
            $endgroup$
            – TwoStones
            May 4 at 10:17
















          • $begingroup$
            Thank you very much!
            $endgroup$
            – TwoStones
            May 4 at 10:17















          $begingroup$
          Thank you very much!
          $endgroup$
          – TwoStones
          May 4 at 10:17




          $begingroup$
          Thank you very much!
          $endgroup$
          – TwoStones
          May 4 at 10:17

















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