Hyper generalized orthogonal Lie algebra

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<math>\begin{pmatrix} \mathbf{A} & V \\ -V^t & 0 \end{pmatrix}<math> belongs to <math>\mathfrak{so}<math>(n+1) if A belongs to <math>\mathfrak{so}<math>(n) and V is a (column) n-vector. Skew-symmetric matrix.

<math>\begin{pmatrix}A & V \\ V^t & 0 \end{pmatrix}<math>

belongs to <math>\mathfrak{so}<math>(n,m+1) if A belongs to <math>\mathfrak{so}<math>(n,m) and V is a (n+m)-vector (including m = 0, of course). Lobachevskian algebra is <math>\mathfrak{so}<math> (n, 1) (not Lorentzian as is usual in the literature, a confusion with his role in Poincare, but neutral is hyperbolic).

New Notation!:<math>\begin{pmatrix}A & V \\ 0 & 0 \end{pmatrix}<math> belongs to <math>\mathfrak{so}<math>(n,m,1) if A belongs to <math>\mathfrak{so}<math>(n,m) and V is a (n+m)-vector. Euclidean algebra is <math>\mathfrak{so}<math>(n,0,1)!. Poincarean algebra is <math>\mathfrak{so}<math>(n,1,1). In general it represents the Lie algebra of the semidirect product of traslations in the space R^n+m with the SO(n, m) which has <math>\mathfrak{so}<math>(n,m) as its Lie algebra.

New Notation:<math>\begin{pmatrix}A & V \\ 0 & 0 \end{pmatrix}<math> belongs to <math>\mathfrak{so}<math>(n,m,l+1) if A belongs to <math>\mathfrak{so}<math>(n,m,l) and V is a (n+m+l)-vector.

In particular:<math>\begin{pmatrix}A & V & X\\ 0 & 0 & t \\0 & 0 & 0\end{pmatrix}<math> belongs to <math>\mathfrak{so}<math>(n,m,2) if A belongs to <math>\mathfrak{so}<math>(n,m) and V and X are (n+m)-vectors. <math>\mathfrak{g}<math>=Galilean algebra is <math>\mathfrak{so}<math>(n,0,2), associated with an iterated semidirect product. (t is a "number", but an important one <math>\mathfrak{g}/[\mathfrak{g},\mathfrak{g}]<math> gives t if n>2. So time is the very conmmutative part of Galilean group).

For completeness we copy here the structure equations dropping nonsense imaginary (in some pages even planckian!) factors. The Lie algebra <math>\mathfrak{g}<math> is spanned by T, X_i, V_i and A_ij (antisymmetric tensor) subject to