generic derivation : delta:=
mat((xi(1,1),0,0,0,0,0),(xi(2,1),xi(2,2),0,0,0,0),(xi(3,1),xi(3,2),xi(2,2) + xi(
1,1),0,0,0),(xi(4,1),xi(4,2),xi(3,2),xi(2,2) + 2*xi(1,1),xi(4,5),xi(4,6)),(xi(5,
1),xi(5,2),0,0,xi(5,5),xi(5,6)),(xi(6,1),xi(6,2),0,0,xi(6,5),xi(6,6)))$

        [0  0  0  0  0  0]
        [                ]
        [0  0  0  0  0  0]
        [                ]
        [0  1  0  0  0  0]
adx1 := [                ]
        [0  0  1  0  0  0]
        [                ]
        [0  0  0  0  0  0]
        [                ]
        [0  0  0  0  0  0]


        [0   0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]
        [                 ]
        [-1  0  0  0  0  0]
adx2 := [                 ]
        [0   0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]


        [0   0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]
adx3 := [                 ]
        [-1  0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]
        [                 ]
        [0   0  0  0  0  0]


The generic nilpotent derivation : the eigenvalues are 0

xi(1,1):=0

xi(2,2):=0

And the matrix A:=(xi(5,5),xi(5,6)),(xi(6,5),xi(6,6)) is nilpotent

We hence get 2 cases according to whether A neq 0 or A=0.

We consider here the case 1 where A neq 0.

In that case, one may suppose A:=((0,1),(0,0)).

xi(5,5):=0

xi(5,6):=1

xi(6,5):=0

xi(6,6):=0

by subtracting adjoints one then may suppose:

xi(3,1):=0,xi(3,2):=0,xi(4,1):=0

delta:=

[   0        0     0  0     0        0   ]
[                                        ]
[xi(2,1)     0     0  0     0        0   ]
[                                        ]
[   0        0     0  0     0        0   ]
[                                        ]
[   0     xi(4,2)  0  0  xi(4,5)  xi(4,6)]
[                                        ]
[xi(5,1)  xi(5,2)  0  0     0        1   ]
[                                        ]
[xi(6,1)  xi(6,2)  0  0     0        0   ]


We denote this delta by the shortform

shortformdelta:={xi(2,1),

                 ss,

                 xi(4,2),

                 xi(4,5),

                 xi(4,6),

                 ss,

                 xi(5,1),

                 xi(5,2),

                 ss,

                 xi(6,1),

                 xi(6,2)}

paramindexeslist:={{2,1},{4,2},{4,5},{4,6},{5,1},{5,2},{6,1},{6,2}}

a:=1$

delta:=
mat((0,0,0,0,0,0),(1,0,0,0,0,0),(0,0,0,0,0,0),(0,1,0,0,0,0),(0,0,0,0,0,1),(1,0,0
,0,0,0))$

shortformdelta:={1,ss,1,0,0,ss,0,0,ss,1,0}$

on resout l'equation {{0,1},0} qui est  maintenant AA:= - (d(0,6) + d(0,2))$

Unknowns: {d(0,6),d(0,2)}
Unknowns: {d(0,6),d(0,2)}
bonne inconnue W:=d(0,6)$

sa valeur doit etre WW:= - d(0,2)$

on resout l'equation {{0,1},1} qui est  maintenant AA:= - (d(1,6) + d(1,2))$

Unknowns: {d(1,6),d(1,2)}
Unknowns: {d(1,6),d(1,2)}
bonne inconnue W:=d(1,6)$

sa valeur doit etre WW:= - d(1,2)$

on resout l'equation {{0,1},2} qui est  maintenant AA:= - d(2,6) - d(2,2) + d(1,
1) + d(0,0)$

Unknowns: {d(2,6),d(2,2),d(1,1),d(0,0)}
Unknowns: {d(2,6),d(2,2),d(1,1),d(0,0)}
bonne inconnue W:=d(2,6)$

sa valeur doit etre WW:= - d(2,2) + d(1,1) + d(0,0)$

on resout l'equation {{0,1},3} qui est  maintenant AA:= - (d(3,6) + d(3,2) + d(2
,0))$

Unknowns: {d(3,6),d(3,2),d(2,0)}
Unknowns: {d(3,6),d(3,2),d(2,0)}
bonne inconnue W:=d(3,6)$

sa valeur doit etre WW:= - (d(3,2) + d(2,0))$

on resout l'equation {{0,1},4} qui est  maintenant AA:= - d(4,6) - d(4,2) - d(3,
0) + d(2,1)$

Unknowns: {d(4,6),d(4,2),d(3,0),d(2,1)}
Unknowns: {d(4,6),d(4,2),d(3,0),d(2,1)}
bonne inconnue W:=d(4,6)$

sa valeur doit etre WW:= - d(4,2) - d(3,0) + d(2,1)$

on resout l'equation {{0,1},5} qui est  maintenant AA:=d(6,1) - d(5,6) - d(5,2)$

Unknowns: {d(6,1),d(5,6),d(5,2)}
Unknowns: {d(6,1),d(5,6),d(5,2)}
bonne inconnue W:=d(6,1)$

sa valeur doit etre WW:=d(5,6) + d(5,2)$

on resout l'equation {{0,1},6} qui est  maintenant AA:= - d(6,6) - d(6,2) + d(1,
1) + d(0,0)$

Unknowns: {d(6,6),d(6,2),d(1,1),d(0,0)}
Unknowns: {d(6,6),d(6,2),d(1,1),d(0,0)}
bonne inconnue W:=d(6,6)$

sa valeur doit etre WW:= - d(6,2) + d(1,1) + d(0,0)$

on resout l'equation {{0,2},0} qui est  maintenant AA:= - d(0,4)$

Unknown: d(0,4)
Unknown: d(0,4)
bonne inconnue W:=d(0,4)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,2},1} qui est  maintenant AA:= - d(1,4)$

Unknown: d(1,4)
Unknown: d(1,4)
bonne inconnue W:=d(1,4)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,2},2} qui est  maintenant AA:= - d(2,4) + d(1,2)$

Unknowns: {d(2,4),d(1,2)}
Unknowns: {d(2,4),d(1,2)}
bonne inconnue W:=d(2,4)$

sa valeur doit etre WW:=d(1,2)$

on resout l'equation {{0,2},3} qui est  maintenant AA:= - d(3,4) + d(1,0)$

Unknowns: {d(3,4),d(1,0)}
Unknowns: {d(3,4),d(1,0)}
bonne inconnue W:=d(3,4)$

sa valeur doit etre WW:=d(1,0)$

on resout l'equation {{0,2},4} qui est  maintenant AA:= - d(4,4) + d(2,2) + d(0,
0)$

Unknowns: {d(4,4),d(2,2),d(0,0)}
Unknowns: {d(4,4),d(2,2),d(0,0)}
bonne inconnue W:=d(4,4)$

sa valeur doit etre WW:=d(2,2) + d(0,0)$

on resout l'equation {{0,2},5} qui est  maintenant AA:=d(6,2) - d(5,4)$

Unknowns: {d(6,2),d(5,4)}
Unknowns: {d(6,2),d(5,4)}
bonne inconnue W:=d(6,2)$

sa valeur doit etre WW:=d(5,4)$

on resout l'equation {{0,2},6} qui est  maintenant AA:= - d(6,4) + d(1,2)$

Unknowns: {d(6,4),d(1,2)}
Unknowns: {d(6,4),d(1,2)}
bonne inconnue W:=d(6,4)$

sa valeur doit etre WW:=d(1,2)$

on resout l'equation {{0,3},2} qui est  maintenant AA:=d(1,3)$

Unknown: d(1,3)
Unknown: d(1,3)
bonne inconnue W:=d(1,3)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,3},4} qui est  maintenant AA:=d(2,3) + d(1,0)$

Unknowns: {d(2,3),d(1,0)}
Unknowns: {d(2,3),d(1,0)}
bonne inconnue W:=d(1,0)$

sa valeur doit etre WW:= - d(2,3)$

on resout l'equation {{0,3},5} qui est  maintenant AA:=d(6,3)$

Unknown: d(6,3)
Unknown: d(6,3)
bonne inconnue W:=d(6,3)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,4},4} qui est  maintenant AA:=d(1,2)$

Unknown: d(1,2)
Unknown: d(1,2)
bonne inconnue W:=d(1,2)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,5},2} qui est  maintenant AA:=d(1,5)$

Unknown: d(1,5)
Unknown: d(1,5)
bonne inconnue W:=d(1,5)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,5},4} qui est  maintenant AA:=d(2,5)$

Unknown: d(2,5)
Unknown: d(2,5)
bonne inconnue W:=d(2,5)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,5},5} qui est  maintenant AA:=d(6,5)$

Unknown: d(6,5)
Unknown: d(6,5)
bonne inconnue W:=d(6,5)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,6},0} qui est  maintenant AA:= - d(0,5)$

Unknown: d(0,5)
Unknown: d(0,5)
bonne inconnue W:=d(0,5)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,6},3} qui est  maintenant AA:= - d(3,5)$

Unknown: d(3,5)
Unknown: d(3,5)
bonne inconnue W:=d(3,5)$

sa valeur doit etre WW:=0$

on resout l'equation {{0,6},4} qui est  maintenant AA:= - d(4,5) - d(2,2) + d(1,
1) + d(0,0)$

Unknowns: {d(4,5),d(2,2),d(1,1),d(0,0)}
Unknowns: {d(4,5),d(2,2),d(1,1),d(0,0)}
bonne inconnue W:=d(4,5)$

sa valeur doit etre WW:= - d(2,2) + d(1,1) + d(0,0)$

on resout l'equation {{0,6},5} qui est  maintenant AA:= - d(5,5) - d(5,4) + d(1,
1) + 2*d(0,0)$

Unknowns: {d(5,5),d(5,4),d(1,1),d(0,0)}
Unknowns: {d(5,5),d(5,4),d(1,1),d(0,0)}
bonne inconnue W:=d(5,4)$

sa valeur doit etre WW:= - d(5,5) + d(1,1) + 2*d(0,0)$

on resout l'equation {{1,2},0} qui est  maintenant AA:= - d(0,3)$

Unknown: d(0,3)
Unknown: d(0,3)
bonne inconnue W:=d(0,3)$

sa valeur doit etre WW:=0$

on resout l'equation {{1,2},2} qui est  maintenant AA:= - (d(2,3) + d(0,2))$

Unknowns: {d(2,3),d(0,2)}
Unknowns: {d(2,3),d(0,2)}
bonne inconnue W:=d(2,3)$

sa valeur doit etre WW:= - d(0,2)$

on resout l'equation {{1,2},3} qui est  maintenant AA:= - d(3,3) + d(2,2) + d(1,
1)$

Unknowns: {d(3,3),d(2,2),d(1,1)}
Unknowns: {d(3,3),d(2,2),d(1,1)}
bonne inconnue W:=d(3,3)$

sa valeur doit etre WW:=d(2,2) + d(1,1)$

on resout l'equation {{1,2},4} qui est  maintenant AA:= - d(4,3) + d(3,2) + d(0,
1)$

Unknowns: {d(4,3),d(3,2),d(0,1)}
Unknowns: {d(4,3),d(3,2),d(0,1)}
bonne inconnue W:=d(4,3)$

sa valeur doit etre WW:=d(3,2) + d(0,1)$

on resout l'equation {{1,2},5} qui est  maintenant AA:= - d(5,3)$

Unknown: d(5,3)
Unknown: d(5,3)
bonne inconnue W:=d(5,3)$

sa valeur doit etre WW:=0$

on resout l'equation {{1,2},6} qui est  maintenant AA:= - d(0,2)$

Unknown: d(0,2)
Unknown: d(0,2)
bonne inconnue W:=d(0,2)$

sa valeur doit etre WW:=0$

on resout l'equation {{1,3},4} qui est  maintenant AA:=2*d(1,1) - d(0,0)$

Unknowns: {d(1,1),d(0,0)}
Unknowns: {d(1,1),d(0,0)}
bonne inconnue W:=d(1,1)$

sa valeur doit etre WW:=d(0,0)/2$

on resout l'equation {{1,3},5} qui est  maintenant AA:=(2*d(5,5) - 5*d(0,0))/2$

Unknowns: {d(5,5),d(0,0)}
Unknowns: {d(5,5),d(0,0)}
bonne inconnue W:=d(5,5)$

sa valeur doit etre WW:=(5*d(0,0))/2$

on resout l'equation {{1,6},3} qui est  maintenant AA:=( - 2*d(2,2) + 3*d(0,0))/
2$

Unknowns: {d(2,2),d(0,0)}
Unknowns: {d(2,2),d(0,0)}
bonne inconnue W:=d(2,2)$

sa valeur doit etre WW:=(3*d(0,0))/2$

on resout l'equation {{1,6},4} qui est  maintenant AA:= - (d(3,2) + d(2,0))$

Unknowns: {d(3,2),d(2,0)}
Unknowns: {d(3,2),d(2,0)}
bonne inconnue W:=d(3,2)$

sa valeur doit etre WW:= - d(2,0)$

on resout l'equation {{1,6},5} qui est  maintenant AA:=d(0,1)$

Unknown: d(0,1)
Unknown: d(0,1)
bonne inconnue W:=d(0,1)$

sa valeur doit etre WW:=0$

Derivation equations to cancel (Reduce output) : \\{{{{0,1},0},0},
{{{0,1},1},0},
{{{0,1},2},0},
{{{0,1},3},0},
{{{0,1},4},0},
{{{0,1},5},0},
{{{0,1},6},0},
{{{0,2},0},0},
{{{0,2},1},0},
{{{0,2},2},0},
{{{0,2},3},0},
{{{0,2},4},0},
{{{0,2},5},0},
{{{0,2},6},0},
{{{0,3},2},0},
{{{0,3},4},0},
{{{0,3},5},0},
{{{0,3},6},0},
{{{0,4},2},0},
{{{0,4},4},0},
{{{0,4},5},0},
{{{0,4},6},0},
{{{0,5},2},0},
{{{0,5},4},0},
{{{0,5},5},0},
{{{0,5},6},0},
{{{0,6},0},0},
{{{0,6},1},0},
{{{0,6},2},0},
{{{0,6},3},0},
{{{0,6},4},0},
{{{0,6},5},0},
{{{0,6},6},0},
{{{1,2},0},0},
{{{1,2},1},0},
{{{1,2},2},0},
{{{1,2},3},0},
{{{1,2},4},0},
{{{1,2},5},0},
{{{1,2},6},0},
{{{1,3},0},0},
{{{1,3},1},0},
{{{1,3},2},0},
{{{1,3},3},0},
{{{1,3},4},0},
{{{1,3},5},0},
{{{1,3},6},0},
{{{1,4},2},0},
{{{1,4},3},0},
{{{1,4},4},0},
{{{1,4},6},0},
{{{1,5},2},0},
{{{1,5},3},0},
{{{1,5},4},0},
{{{1,5},6},0},
{{{1,6},2},0},
{{{1,6},3},0},
{{{1,6},4},0},
{{{1,6},5},0},
{{{1,6},6},0},
{{{2,3},3},0},
{{{2,3},4},0},
{{{2,4},3},0},
{{{2,4},4},0},
{{{2,5},3},0},
{{{2,5},4},0},
{{{2,6},3},0},
{{{2,6},4},0},
{{{2,6},5},0},
{{{3,4},4},0},
{{{3,5},4},0},
{{{3,6},4},0},
{{{3,6},5},0},
{{{4,6},5},0},
{{{5,6},5},0}}$

Il n'y a pas de phase 2$

derivation generique de gtildedelta:$

MATD:=
mat((d(0,0),0,0,0,0,0,0),(0,d(0,0)/2,0,0,0,0,0),(d(2,0),d(2,1),(3*d(0,0))/2,0,0,
0,0),(d(3,0),d(3,1), - d(2,0),2*d(0,0),0,0,0),(d(4,0),d(4,1),d(4,2), - d(2,0),(5
*d(0,0))/2,0, - d(4,2) - d(3,0) + d(2,1)),(d(5,0),d(5,1),d(5,2),0,0,(5*d(0,0))/2
,d(5,6)),(d(6,0),d(5,6) + d(5,2),0,0,0,0,(3*d(0,0))/2))$

pour delta:=

[0  0  0  0  0  0]
[                ]
[1  0  0  0  0  0]
[                ]
[0  0  0  0  0  0]
[                ]
[0  1  0  0  0  0]
[                ]
[0  0  0  0  0  1]
[                ]
[1  0  0  0  0  0]


pour shortformdelta:={1,ss,1,0,0,ss,0,0,ss,1,0}

Unknowns: {d(6,0),
d(5,6),
d(5,2),
d(5,1),
d(5,0),
d(4,2),
d(4,1),
d(4,0),
d(3,1),
d(3,0),
d(2,1),
d(2,0),
d(0,0)}
Unknowns: {d(6,0),
d(5,6),
d(5,2),
d(5,1),
d(5,0),
d(4,2),
d(4,1),
d(4,0),
d(3,1),
d(3,0),
d(2,1),
d(2,0),
d(0,0)}
listeparametresMATD{d(6,0),
d(5,6),
d(5,2),
d(5,1),
d(5,0),
d(4,2),
d(4,1),
d(4,0),
d(3,1),
d(3,0),
d(2,1),
d(2,0),
d(0,0)}$

dim Der(gtildedelta):=13$

t1:=D(0,0):=

[1   0    0   0   0    0    0 ]
[                             ]
[    1                        ]
[0  ---   0   0   0    0    0 ]
[    2                        ]
[                             ]
[         3                   ]
[0   0   ---  0   0    0    0 ]
[         2                   ]
[                             ]
[0   0    0   2   0    0    0 ]
[                             ]
[                 5           ]
[0   0    0   0  ---   0    0 ]
[                 2           ]
[                             ]
[                      5      ]
[0   0    0   0   0   ---   0 ]
[                      2      ]
[                             ]
[                           3 ]
[0   0    0   0   0    0   ---]
[                           2 ]


rank 1 with maximal torus t1

1


matrice de passage de la base X(0)=delta, X(1),..., X(6) a une base  diagonali\
sant le tore maximal: on peut prendre

P:=

[1  0  0  0  0  0  0]
[                   ]
[0  1  0  0  0  0  0]
[                   ]
[0  0  1  0  0  0  0]
[                   ]
[0  0  0  1  0  0  0]
[                   ]
[0  0  0  0  1  0  0]
[                   ]
[0  0  0  0  0  1  0]
[                   ]
[0  0  0  0  0  0  1]


P**(-1)*t1*P:=

[1   0    0   0   0    0    0 ]
[                             ]
[    1                        ]
[0  ---   0   0   0    0    0 ]
[    2                        ]
[                             ]
[         3                   ]
[0   0   ---  0   0    0    0 ]
[         2                   ]
[                             ]
[0   0    0   2   0    0    0 ]
[                             ]
[                 5           ]
[0   0    0   0  ---   0    0 ]
[                 2           ]
[                             ]
[                      5      ]
[0   0    0   0   0   ---   0 ]
[                      2      ]
[                             ]
[                           3 ]
[0   0    0   0   0    0   ---]
[                           2 ]


matrice des derivations dans cette base diagonalisante Y(1),...,Y(7):

P**(-1)*MATD*P:=
mat((d(0,0),0,0,0,0,0,0),(0,d(0,0)/2,0,0,0,0,0),(d(2,0),d(2,1),(3*d(0,0))/2,0,0,
0,0),(d(3,0),d(3,1), - d(2,0),2*d(0,0),0,0,0),(d(4,0),d(4,1),d(4,2), - d(2,0),(5
*d(0,0))/2,0, - d(4,2) - d(3,0) + d(2,1)),(d(5,0),d(5,1),d(5,2),0,0,(5*d(0,0))/2
,d(5,6)),(d(6,0),d(5,6) + d(5,2),0,0,0,0,(3*d(0,0))/2))$

PP:=

[1  0  0  0  0  0  0]
[                   ]
[0  1  0  0  0  0  0]
[                   ]
[0  0  1  0  0  0  0]
[                   ]
[0  0  0  1  0  0  0]
[                   ]
[0  0  0  0  1  0  0]
[                   ]
[0  0  0  0  0  1  0]
[                   ]
[0  0  0  0  0  0  1]


avec PP:=P*Q:=

[1  0  0  0  0  0  0]
[                   ]
[0  1  0  0  0  0  0]
[                   ]
[0  0  1  0  0  0  0]
[                   ]
[0  0  0  1  0  0  0]
[                   ]
[0  0  0  0  1  0  0]
[                   ]
[0  0  0  0  0  1  0]
[                   ]
[0  0  0  0  0  0  1]


MATDDIAGONALISE:=

mat((d(0,0),0,0,0,0,0,0),

        d(0,0)
    (0,--------,0,0,0,0,0),
          2

                    3*d(0,0)
    (d(2,0),d(2,1),----------,0,0,0,0),
                       2

    (d(3,0),d(3,1), - d(2,0),2*d(0,0),0,0,0),

                                     5*d(0,0)
    (d(4,0),d(4,1),d(4,2), - d(2,0),----------,0, - d(4,2) - d(3,0) + d(2,1)),
                                        2

                               5*d(0,0)
    (d(5,0),d(5,1),d(5,2),0,0,----------,d(5,6)),
                                  2

                                     3*d(0,0)
    (d(6,0),d(5,6) + d(5,2),0,0,0,0,----------))
                                        2


on voit apparaitre les poids sur la diagonale

r(1) := d(0,0)

         d(0,0)
r(2) := --------
           2

         3*d(0,0)
r(3) := ----------
            2

r(4) := 2*d(0,0)

         5*d(0,0)
r(5) := ----------
            2

         5*d(0,0)
r(6) := ----------
            2

         3*d(0,0)
r(7) := ----------
            2

r(1) := 2*gamma1

r(2) := gamma1

r(3) := 3*gamma1

r(4) := 4*gamma1

r(5) := 5*gamma1

r(6) := 5*gamma1

r(7) := 3*gamma1

Le systeme de poids est le systeme 1.18

calcul de relations de commutation de la base diaY(j) diagonalisant le tore

listcommutateursdesx := {{{0,1},x(6) + x(2)},

   {{0,2},x(4)},

   {{0,3},0},

   {{0,4},0},

   {{0,5},0},

   {{0,6},x(5)},

   {{1,2},x(3)},

   {{1,3},x(4)},

   {{1,4},0},

   {{1,5},0},

   {{1,6},0},

   {{2,3},0},

   {{2,4},0},

   {{2,5},0},

   {{2,6},0},

   {{3,4},0},

   {{3,5},0},

   {{3,6},0},

   {{4,5},0},

   {{4,6},0},

   {{5,6},0}}

diaY(1):=x(0)

diaY(2):=x(1)

diaY(3):=x(2)

diaY(4):=x(3)

diaY(5):=x(4)

diaY(6):=x(5)

diaY(7):=x(6)

liste des commutateurs des diaY(i) :$

listcommutateurdesdiaY:={{{1,2},diay(7) + diay(3)},
{{1,3},diay(5)},
{{1,4},0},
{{1,5},0},
{{1,6},0},
{{1,7},diay(6)},
{{2,3},diay(4)},
{{2,4},diay(5)},
{{2,5},0},
{{2,6},0},
{{2,7},0},
{{3,4},0},
{{3,5},0},
{{3,6},0},
{{3,7},0},
{{4,5},0},
{{4,6},0},
{{4,7},0},
{{5,6},0},
{{5,7},0},
{{6,7},0}}$

Now we make explicit the isomorphism with an algebra of the book:$

Namely g_{7,1.18}$

i.e. we go from the basis diaY(i) to the new basis ZZ(i) defined by the matrix:$

on pose :$

avec comme matrice de changement de base :$

mat((0,-1,0,0,0,0,0),(1,0,0,0,0,0,0),(0,0,0,1,0,0,0),(0,0,0,0,1,0,0),(0,0,0,0,0,
-1,1),(0,0,0,0,0,-1,0),(0,0,1,1,0,0,0))$

det(isom):= 1$

ZZ(1):=diay(2)$

ZZ(2):= - diay(1)$

ZZ(3):=diay(7)$

ZZ(4):=diay(7) + diay(3)$

ZZ(5):=diay(4)$

ZZ(6):= - (diay(6) + diay(5))$

ZZ(7):=diay(5)$

listcommutateursdesZZ:=$

{{1,2},zz(4)}$

{{1,3},0}$

{{1,4},zz(5)}$

{{1,5},zz(7)}$

{{1,6},0}$

{{1,7},0}$

{{2,3},zz(7) + zz(6)}$

{{2,4},zz(6)}$

{{2,5},0}$

{{2,6},0}$

{{2,7},0}$

{{3,4},0}$

{{3,5},0}$

{{3,6},0}$

{{3,7},0}$

{{4,5},0}$

{{4,6},0}$

{{4,7},0}$

{{5,6},0}$

{{5,7},0}$

{{6,7},0}$

We get the commutation relations of$

g_{7,1.18}$

Et cela pour a:=1$

shortformdelta:={1,ss,1,0,0,ss,0,0,ss,1,0}$

delta:=
mat((0,0,0,0,0,0),(1,0,0,0,0,0),(0,0,0,0,0,0),(0,1,0,0,0,0),(0,0,0,0,0,1),(1,0,0
,0,0,0))$

The isomorphism from g_{7,1.18} to gtildedelta$

was constructed in 2 steps and is given by$

the product matrix P*isom:=
mat((0,-1,0,0,0,0,0),(1,0,0,0,0,0,0),(0,0,0,1,0,0,0),(0,0,0,0,1,0,0),(0,0,0,0,0,
-1,1),(0,0,0,0,0,-1,0),(0,0,1,1,0,0,0))$

which we record here under the name PSI$