non nilpotent Lie algebras












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Let $L$ be a nonperfect Lie algebra (i.e. $L ne [L, L]$) which is
not nilpotent. Is there a ideal of $L$ such as $M$ such that intersection drived subalgebra of $L$ and $Z(M)$ is nonzero?










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    0












    $begingroup$


    Let $L$ be a nonperfect Lie algebra (i.e. $L ne [L, L]$) which is
    not nilpotent. Is there a ideal of $L$ such as $M$ such that intersection drived subalgebra of $L$ and $Z(M)$ is nonzero?










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Let $L$ be a nonperfect Lie algebra (i.e. $L ne [L, L]$) which is
      not nilpotent. Is there a ideal of $L$ such as $M$ such that intersection drived subalgebra of $L$ and $Z(M)$ is nonzero?










      share|cite|improve this question











      $endgroup$




      Let $L$ be a nonperfect Lie algebra (i.e. $L ne [L, L]$) which is
      not nilpotent. Is there a ideal of $L$ such as $M$ such that intersection drived subalgebra of $L$ and $Z(M)$ is nonzero?







      group-theory lie-algebras






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      edited Dec 18 '18 at 10:35









      Andreas Caranti

      56.6k34395




      56.6k34395










      asked Dec 18 '18 at 5:56









      AfsanehAfsaneh

      83




      83






















          1 Answer
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          $begingroup$

          Yes, there is such an ideal. Take $L$ to be the $2$-dimensional nonabelian Lie algebra with basis $e_1,e_2$ and Lie bracket $[e_1,e_2]=e_1$ and the ideal $M=langle e_1rangle$. Then $L$ is not nilpotent, $Lneq [L,L]$ and $M$ is an ideal with $Z(M)=[L,L]neq 0$.



          In general, however, this need not be true. Take $L=mathfrak{gl}_2(Bbb{C})=mathfrak{sl}_2(Bbb{C})oplus Bbb{C}$. Then $L$ is not perfect and not nilpotent, but $Z(M)$ is either zero or $Bbb{C}$ for all ideals $M$, and the intersection with $[L,L]$ is zero.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thank you for your help.
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:35










          • $begingroup$
            Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:38












          • $begingroup$
            In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
            $endgroup$
            – Dietrich Burde
            Dec 18 '18 at 12:18











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          $begingroup$

          Yes, there is such an ideal. Take $L$ to be the $2$-dimensional nonabelian Lie algebra with basis $e_1,e_2$ and Lie bracket $[e_1,e_2]=e_1$ and the ideal $M=langle e_1rangle$. Then $L$ is not nilpotent, $Lneq [L,L]$ and $M$ is an ideal with $Z(M)=[L,L]neq 0$.



          In general, however, this need not be true. Take $L=mathfrak{gl}_2(Bbb{C})=mathfrak{sl}_2(Bbb{C})oplus Bbb{C}$. Then $L$ is not perfect and not nilpotent, but $Z(M)$ is either zero or $Bbb{C}$ for all ideals $M$, and the intersection with $[L,L]$ is zero.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thank you for your help.
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:35










          • $begingroup$
            Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:38












          • $begingroup$
            In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
            $endgroup$
            – Dietrich Burde
            Dec 18 '18 at 12:18
















          1












          $begingroup$

          Yes, there is such an ideal. Take $L$ to be the $2$-dimensional nonabelian Lie algebra with basis $e_1,e_2$ and Lie bracket $[e_1,e_2]=e_1$ and the ideal $M=langle e_1rangle$. Then $L$ is not nilpotent, $Lneq [L,L]$ and $M$ is an ideal with $Z(M)=[L,L]neq 0$.



          In general, however, this need not be true. Take $L=mathfrak{gl}_2(Bbb{C})=mathfrak{sl}_2(Bbb{C})oplus Bbb{C}$. Then $L$ is not perfect and not nilpotent, but $Z(M)$ is either zero or $Bbb{C}$ for all ideals $M$, and the intersection with $[L,L]$ is zero.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thank you for your help.
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:35










          • $begingroup$
            Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:38












          • $begingroup$
            In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
            $endgroup$
            – Dietrich Burde
            Dec 18 '18 at 12:18














          1












          1








          1





          $begingroup$

          Yes, there is such an ideal. Take $L$ to be the $2$-dimensional nonabelian Lie algebra with basis $e_1,e_2$ and Lie bracket $[e_1,e_2]=e_1$ and the ideal $M=langle e_1rangle$. Then $L$ is not nilpotent, $Lneq [L,L]$ and $M$ is an ideal with $Z(M)=[L,L]neq 0$.



          In general, however, this need not be true. Take $L=mathfrak{gl}_2(Bbb{C})=mathfrak{sl}_2(Bbb{C})oplus Bbb{C}$. Then $L$ is not perfect and not nilpotent, but $Z(M)$ is either zero or $Bbb{C}$ for all ideals $M$, and the intersection with $[L,L]$ is zero.






          share|cite|improve this answer











          $endgroup$



          Yes, there is such an ideal. Take $L$ to be the $2$-dimensional nonabelian Lie algebra with basis $e_1,e_2$ and Lie bracket $[e_1,e_2]=e_1$ and the ideal $M=langle e_1rangle$. Then $L$ is not nilpotent, $Lneq [L,L]$ and $M$ is an ideal with $Z(M)=[L,L]neq 0$.



          In general, however, this need not be true. Take $L=mathfrak{gl}_2(Bbb{C})=mathfrak{sl}_2(Bbb{C})oplus Bbb{C}$. Then $L$ is not perfect and not nilpotent, but $Z(M)$ is either zero or $Bbb{C}$ for all ideals $M$, and the intersection with $[L,L]$ is zero.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Dec 18 '18 at 9:25

























          answered Dec 18 '18 at 9:02









          Dietrich BurdeDietrich Burde

          79.4k647103




          79.4k647103












          • $begingroup$
            Thank you for your help.
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:35










          • $begingroup$
            Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:38












          • $begingroup$
            In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
            $endgroup$
            – Dietrich Burde
            Dec 18 '18 at 12:18


















          • $begingroup$
            Thank you for your help.
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:35










          • $begingroup$
            Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
            $endgroup$
            – Afsaneh
            Dec 18 '18 at 11:38












          • $begingroup$
            In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
            $endgroup$
            – Dietrich Burde
            Dec 18 '18 at 12:18
















          $begingroup$
          Thank you for your help.
          $endgroup$
          – Afsaneh
          Dec 18 '18 at 11:35




          $begingroup$
          Thank you for your help.
          $endgroup$
          – Afsaneh
          Dec 18 '18 at 11:35












          $begingroup$
          Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
          $endgroup$
          – Afsaneh
          Dec 18 '18 at 11:38






          $begingroup$
          Let L be a non nilpotent Lie algebra. Is there a non abelain nilpotent subalgebra of L?
          $endgroup$
          – Afsaneh
          Dec 18 '18 at 11:38














          $begingroup$
          In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
          $endgroup$
          – Dietrich Burde
          Dec 18 '18 at 12:18




          $begingroup$
          In general, no. Take $L$ to be the $2$-dimensional nonabelian Lie algebra as above.
          $endgroup$
          – Dietrich Burde
          Dec 18 '18 at 12:18


















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