About quotients of Lower Exponent$-p$ central Series












2














Let $G$ be a finite $p-$group of number of generators $d$ and exponent$-p$ class $c$, that is $c$ is the smallest integer satisfying $P_c(G) =1$ in the series
$$
G=P_0(G) geq ...geq P_{i-1}(G)geq P_{i}(G)geq ...
$$

Where $P_{i}(G)= [P_{i-1}(G), G]{P_{i-1}(G)}^p$.



A group $H$ is a descendant of $G$ if $H$ has generator number $d$ and the quotient $H/P_c(H)$ is isomorphic to $G$



A group is an immediate descendant of $G$ if it is a descendant of $G$ and has an exponent$-p$ class $c+1$.



1Can you show me "in details" why $G/P_1(G)$ is an elementary abelian?
What is its order then?



2 Is $G$ a descendant of $G/P_1(G)$?



3 For $i<c$, is $G/P_{i+1}(G)$ is an "immediate descendant" of $G/P_i(G)$?



My best regards










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    2














    Let $G$ be a finite $p-$group of number of generators $d$ and exponent$-p$ class $c$, that is $c$ is the smallest integer satisfying $P_c(G) =1$ in the series
    $$
    G=P_0(G) geq ...geq P_{i-1}(G)geq P_{i}(G)geq ...
    $$

    Where $P_{i}(G)= [P_{i-1}(G), G]{P_{i-1}(G)}^p$.



    A group $H$ is a descendant of $G$ if $H$ has generator number $d$ and the quotient $H/P_c(H)$ is isomorphic to $G$



    A group is an immediate descendant of $G$ if it is a descendant of $G$ and has an exponent$-p$ class $c+1$.



    1Can you show me "in details" why $G/P_1(G)$ is an elementary abelian?
    What is its order then?



    2 Is $G$ a descendant of $G/P_1(G)$?



    3 For $i<c$, is $G/P_{i+1}(G)$ is an "immediate descendant" of $G/P_i(G)$?



    My best regards










    share|cite|improve this question



























      2












      2








      2


      2





      Let $G$ be a finite $p-$group of number of generators $d$ and exponent$-p$ class $c$, that is $c$ is the smallest integer satisfying $P_c(G) =1$ in the series
      $$
      G=P_0(G) geq ...geq P_{i-1}(G)geq P_{i}(G)geq ...
      $$

      Where $P_{i}(G)= [P_{i-1}(G), G]{P_{i-1}(G)}^p$.



      A group $H$ is a descendant of $G$ if $H$ has generator number $d$ and the quotient $H/P_c(H)$ is isomorphic to $G$



      A group is an immediate descendant of $G$ if it is a descendant of $G$ and has an exponent$-p$ class $c+1$.



      1Can you show me "in details" why $G/P_1(G)$ is an elementary abelian?
      What is its order then?



      2 Is $G$ a descendant of $G/P_1(G)$?



      3 For $i<c$, is $G/P_{i+1}(G)$ is an "immediate descendant" of $G/P_i(G)$?



      My best regards










      share|cite|improve this question















      Let $G$ be a finite $p-$group of number of generators $d$ and exponent$-p$ class $c$, that is $c$ is the smallest integer satisfying $P_c(G) =1$ in the series
      $$
      G=P_0(G) geq ...geq P_{i-1}(G)geq P_{i}(G)geq ...
      $$

      Where $P_{i}(G)= [P_{i-1}(G), G]{P_{i-1}(G)}^p$.



      A group $H$ is a descendant of $G$ if $H$ has generator number $d$ and the quotient $H/P_c(H)$ is isomorphic to $G$



      A group is an immediate descendant of $G$ if it is a descendant of $G$ and has an exponent$-p$ class $c+1$.



      1Can you show me "in details" why $G/P_1(G)$ is an elementary abelian?
      What is its order then?



      2 Is $G$ a descendant of $G/P_1(G)$?



      3 For $i<c$, is $G/P_{i+1}(G)$ is an "immediate descendant" of $G/P_i(G)$?



      My best regards







      abstract-algebra group-theory finite-groups computational-mathematics p-groups






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      edited Dec 27 '18 at 1:01









      the_fox

      2,43411431




      2,43411431










      asked Dec 3 '18 at 13:13









      A.Messab

      507




      507






















          1 Answer
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          $P_1(G) = [G,G]G^p$. Then $G/P_1(G)$ is abelian because $[G,G] le P_1(G)$. It has exponent $p$, and is therefore elementary abelian because $G^p le P_1(G)$.



          The answers to 2 and 3 are both yes. Let $Q = G/P_1(G)$. Then, since $P_1(G) = Phi(G)$, the generator numbers of $Q$ and $G$ are the same. Since $Q$ has exponent $p$-class $1$, it follows that $G$ is a descendant of $Q$.



          3 also follows directly from the definition of immediate descendant.






          share|cite|improve this answer





















          • Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
            – A.Messab
            Dec 4 '18 at 9:19










          • An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
            – Derek Holt
            Dec 4 '18 at 10:08










          • know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
            – A.Messab
            Dec 4 '18 at 10:14






          • 1




            Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
            – Derek Holt
            Dec 4 '18 at 11:02












          • Many many thanks professor, that is so helpful demonstration
            – A.Messab
            Dec 4 '18 at 11:09











          Your Answer





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          1 Answer
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          $P_1(G) = [G,G]G^p$. Then $G/P_1(G)$ is abelian because $[G,G] le P_1(G)$. It has exponent $p$, and is therefore elementary abelian because $G^p le P_1(G)$.



          The answers to 2 and 3 are both yes. Let $Q = G/P_1(G)$. Then, since $P_1(G) = Phi(G)$, the generator numbers of $Q$ and $G$ are the same. Since $Q$ has exponent $p$-class $1$, it follows that $G$ is a descendant of $Q$.



          3 also follows directly from the definition of immediate descendant.






          share|cite|improve this answer





















          • Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
            – A.Messab
            Dec 4 '18 at 9:19










          • An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
            – Derek Holt
            Dec 4 '18 at 10:08










          • know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
            – A.Messab
            Dec 4 '18 at 10:14






          • 1




            Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
            – Derek Holt
            Dec 4 '18 at 11:02












          • Many many thanks professor, that is so helpful demonstration
            – A.Messab
            Dec 4 '18 at 11:09
















          4














          $P_1(G) = [G,G]G^p$. Then $G/P_1(G)$ is abelian because $[G,G] le P_1(G)$. It has exponent $p$, and is therefore elementary abelian because $G^p le P_1(G)$.



          The answers to 2 and 3 are both yes. Let $Q = G/P_1(G)$. Then, since $P_1(G) = Phi(G)$, the generator numbers of $Q$ and $G$ are the same. Since $Q$ has exponent $p$-class $1$, it follows that $G$ is a descendant of $Q$.



          3 also follows directly from the definition of immediate descendant.






          share|cite|improve this answer





















          • Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
            – A.Messab
            Dec 4 '18 at 9:19










          • An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
            – Derek Holt
            Dec 4 '18 at 10:08










          • know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
            – A.Messab
            Dec 4 '18 at 10:14






          • 1




            Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
            – Derek Holt
            Dec 4 '18 at 11:02












          • Many many thanks professor, that is so helpful demonstration
            – A.Messab
            Dec 4 '18 at 11:09














          4












          4








          4






          $P_1(G) = [G,G]G^p$. Then $G/P_1(G)$ is abelian because $[G,G] le P_1(G)$. It has exponent $p$, and is therefore elementary abelian because $G^p le P_1(G)$.



          The answers to 2 and 3 are both yes. Let $Q = G/P_1(G)$. Then, since $P_1(G) = Phi(G)$, the generator numbers of $Q$ and $G$ are the same. Since $Q$ has exponent $p$-class $1$, it follows that $G$ is a descendant of $Q$.



          3 also follows directly from the definition of immediate descendant.






          share|cite|improve this answer












          $P_1(G) = [G,G]G^p$. Then $G/P_1(G)$ is abelian because $[G,G] le P_1(G)$. It has exponent $p$, and is therefore elementary abelian because $G^p le P_1(G)$.



          The answers to 2 and 3 are both yes. Let $Q = G/P_1(G)$. Then, since $P_1(G) = Phi(G)$, the generator numbers of $Q$ and $G$ are the same. Since $Q$ has exponent $p$-class $1$, it follows that $G$ is a descendant of $Q$.



          3 also follows directly from the definition of immediate descendant.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 3 '18 at 17:31









          Derek Holt

          52.6k53570




          52.6k53570












          • Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
            – A.Messab
            Dec 4 '18 at 9:19










          • An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
            – Derek Holt
            Dec 4 '18 at 10:08










          • know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
            – A.Messab
            Dec 4 '18 at 10:14






          • 1




            Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
            – Derek Holt
            Dec 4 '18 at 11:02












          • Many many thanks professor, that is so helpful demonstration
            – A.Messab
            Dec 4 '18 at 11:09


















          • Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
            – A.Messab
            Dec 4 '18 at 9:19










          • An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
            – Derek Holt
            Dec 4 '18 at 10:08










          • know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
            – A.Messab
            Dec 4 '18 at 10:14






          • 1




            Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
            – Derek Holt
            Dec 4 '18 at 11:02












          • Many many thanks professor, that is so helpful demonstration
            – A.Messab
            Dec 4 '18 at 11:09
















          Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
          – A.Messab
          Dec 4 '18 at 9:19




          Thank you very much for your answer, I understood every thing but the fact that "it has exponent $p$ and therefore elementary abelian because $G^p geq P_1(G)$", please some explanation.
          – A.Messab
          Dec 4 '18 at 9:19












          An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
          – Derek Holt
          Dec 4 '18 at 10:08




          An abelian group $G$ in which, for some prime $p$, $g^p=1$ for all $g in G$ is an elementary abelian $p$-group.
          – Derek Holt
          Dec 4 '18 at 10:08












          know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
          – A.Messab
          Dec 4 '18 at 10:14




          know the definition, but why if it is a quotient of some group containing $G^p$ it is elementary abelian, and of exponent $p$?
          – A.Messab
          Dec 4 '18 at 10:14




          1




          1




          Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
          – Derek Holt
          Dec 4 '18 at 11:02






          Let $K=P_1(G) = [G,G]G^p$ and $Q=G/K$. Then, for any $gK,hK in Q$, $[gK,hK]=[g,h]K = K$, since $[G,G] le K$, so $Q$ is abelian. Also, for any $gK in Q$, $(gK)^p = g^pK = K$ because $g^p in G^p le K$. So $Q$ is elementary abelian.
          – Derek Holt
          Dec 4 '18 at 11:02














          Many many thanks professor, that is so helpful demonstration
          – A.Messab
          Dec 4 '18 at 11:09




          Many many thanks professor, that is so helpful demonstration
          – A.Messab
          Dec 4 '18 at 11:09


















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