Classification of metric Lie Algebras of dimension 7?












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I want to classify all metric two-step Lie algebras of dimension 7. Clearly, the dimension of the center of such Lie algebras is $leq 5$. So, I have to consider 5 cases separately, where the dimension of center is $1,2,cdots text{or}, 5$. Let $mathfrak{g}$ is a metric seven dimensional Lie algebra and $mathfrak{h}$ is its one dimensional center. We consider $mathfrak{a}_3$ is a $3-$dimensional vector subspace of $mathfrak{g}$ such that $[mathfrak{a}_3 ,mathfrak{a}_3]=mathfrak{h}$. There is a unique vector subspace $mathfrak{b}_3$ of $mathfrak{a}$ which is complementary subspace of $mathfrak{a}_3$ and commutes with $mathfrak{a}_3$. Then one can choose ${e_1,cdots ,e_7}$ an orthonormal basis of $mathfrak{g}$ such that $mathfrak{h}=text{span}langle e_7rangle$ and ${e_1,e_2,e_3}$ is an orthonormal basis of $mathfrak{a}_3$. We have
$$[e_i,e_j]=lambda_{ij} e_7,qquad i,jin {1,cdots,6}$$
where $0neq lambda_{ij}=-lambda_{ji}$. I want to find a new orthonormal basis to show that $mathfrak{g}$ is metric Heisenberg algebra.



Any suggestion is highly appreciated?










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  • 1




    $begingroup$
    A classification might be already available. In principle, one can use the work of Ines Kath. Here is a classification of metric nilpotent Lie algebras with commutator dimension $2$, up to dimension $10$. I will try to search more, if you want.
    $endgroup$
    – Dietrich Burde
    Jan 1 at 13:17


















2












$begingroup$


I want to classify all metric two-step Lie algebras of dimension 7. Clearly, the dimension of the center of such Lie algebras is $leq 5$. So, I have to consider 5 cases separately, where the dimension of center is $1,2,cdots text{or}, 5$. Let $mathfrak{g}$ is a metric seven dimensional Lie algebra and $mathfrak{h}$ is its one dimensional center. We consider $mathfrak{a}_3$ is a $3-$dimensional vector subspace of $mathfrak{g}$ such that $[mathfrak{a}_3 ,mathfrak{a}_3]=mathfrak{h}$. There is a unique vector subspace $mathfrak{b}_3$ of $mathfrak{a}$ which is complementary subspace of $mathfrak{a}_3$ and commutes with $mathfrak{a}_3$. Then one can choose ${e_1,cdots ,e_7}$ an orthonormal basis of $mathfrak{g}$ such that $mathfrak{h}=text{span}langle e_7rangle$ and ${e_1,e_2,e_3}$ is an orthonormal basis of $mathfrak{a}_3$. We have
$$[e_i,e_j]=lambda_{ij} e_7,qquad i,jin {1,cdots,6}$$
where $0neq lambda_{ij}=-lambda_{ji}$. I want to find a new orthonormal basis to show that $mathfrak{g}$ is metric Heisenberg algebra.



Any suggestion is highly appreciated?










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    A classification might be already available. In principle, one can use the work of Ines Kath. Here is a classification of metric nilpotent Lie algebras with commutator dimension $2$, up to dimension $10$. I will try to search more, if you want.
    $endgroup$
    – Dietrich Burde
    Jan 1 at 13:17
















2












2








2





$begingroup$


I want to classify all metric two-step Lie algebras of dimension 7. Clearly, the dimension of the center of such Lie algebras is $leq 5$. So, I have to consider 5 cases separately, where the dimension of center is $1,2,cdots text{or}, 5$. Let $mathfrak{g}$ is a metric seven dimensional Lie algebra and $mathfrak{h}$ is its one dimensional center. We consider $mathfrak{a}_3$ is a $3-$dimensional vector subspace of $mathfrak{g}$ such that $[mathfrak{a}_3 ,mathfrak{a}_3]=mathfrak{h}$. There is a unique vector subspace $mathfrak{b}_3$ of $mathfrak{a}$ which is complementary subspace of $mathfrak{a}_3$ and commutes with $mathfrak{a}_3$. Then one can choose ${e_1,cdots ,e_7}$ an orthonormal basis of $mathfrak{g}$ such that $mathfrak{h}=text{span}langle e_7rangle$ and ${e_1,e_2,e_3}$ is an orthonormal basis of $mathfrak{a}_3$. We have
$$[e_i,e_j]=lambda_{ij} e_7,qquad i,jin {1,cdots,6}$$
where $0neq lambda_{ij}=-lambda_{ji}$. I want to find a new orthonormal basis to show that $mathfrak{g}$ is metric Heisenberg algebra.



Any suggestion is highly appreciated?










share|cite|improve this question











$endgroup$




I want to classify all metric two-step Lie algebras of dimension 7. Clearly, the dimension of the center of such Lie algebras is $leq 5$. So, I have to consider 5 cases separately, where the dimension of center is $1,2,cdots text{or}, 5$. Let $mathfrak{g}$ is a metric seven dimensional Lie algebra and $mathfrak{h}$ is its one dimensional center. We consider $mathfrak{a}_3$ is a $3-$dimensional vector subspace of $mathfrak{g}$ such that $[mathfrak{a}_3 ,mathfrak{a}_3]=mathfrak{h}$. There is a unique vector subspace $mathfrak{b}_3$ of $mathfrak{a}$ which is complementary subspace of $mathfrak{a}_3$ and commutes with $mathfrak{a}_3$. Then one can choose ${e_1,cdots ,e_7}$ an orthonormal basis of $mathfrak{g}$ such that $mathfrak{h}=text{span}langle e_7rangle$ and ${e_1,e_2,e_3}$ is an orthonormal basis of $mathfrak{a}_3$. We have
$$[e_i,e_j]=lambda_{ij} e_7,qquad i,jin {1,cdots,6}$$
where $0neq lambda_{ij}=-lambda_{ji}$. I want to find a new orthonormal basis to show that $mathfrak{g}$ is metric Heisenberg algebra.



Any suggestion is highly appreciated?







lie-groups lie-algebras






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share|cite|improve this question













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edited Jan 1 at 11:31







Albert

















asked Jan 1 at 10:43









AlbertAlbert

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  • 1




    $begingroup$
    A classification might be already available. In principle, one can use the work of Ines Kath. Here is a classification of metric nilpotent Lie algebras with commutator dimension $2$, up to dimension $10$. I will try to search more, if you want.
    $endgroup$
    – Dietrich Burde
    Jan 1 at 13:17
















  • 1




    $begingroup$
    A classification might be already available. In principle, one can use the work of Ines Kath. Here is a classification of metric nilpotent Lie algebras with commutator dimension $2$, up to dimension $10$. I will try to search more, if you want.
    $endgroup$
    – Dietrich Burde
    Jan 1 at 13:17










1




1




$begingroup$
A classification might be already available. In principle, one can use the work of Ines Kath. Here is a classification of metric nilpotent Lie algebras with commutator dimension $2$, up to dimension $10$. I will try to search more, if you want.
$endgroup$
– Dietrich Burde
Jan 1 at 13:17






$begingroup$
A classification might be already available. In principle, one can use the work of Ines Kath. Here is a classification of metric nilpotent Lie algebras with commutator dimension $2$, up to dimension $10$. I will try to search more, if you want.
$endgroup$
– Dietrich Burde
Jan 1 at 13:17












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