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

        [0  0  0  0  0  0]
        [                ]
        [0  0  0  0  0  0]
        [                ]
        [0  0  0  0  0  0]
adx1 := [                ]
        [0  0  0  0  0  0]
        [                ]
        [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]
adx2 := [                ]
        [0  0  0  0  0  0]
        [                ]
        [0  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]
adx3 := [                 ]
        [0   0  0  0  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  0  0]
adx4 := [                 ]
        [0  0   0  0  0  0]
        [                 ]
        [0  -1  0  0  0  0]
        [                 ]
        [0  0   0  0  0  0]


The generic nilpotent derivation : the eigenvalues are 0

xi(3,3):= - xi(1,1)

xi(6,6):=0

And the matrix A:=

[xi(1,1)  xi(1,2)   xi(1,3)     xi(1,4)  ]
[                                        ]
[xi(2,1)  xi(2,2)   xi(1,4)     xi(2,4)  ]
[                                        ]
[xi(3,1)  xi(3,2)   - xi(1,1)   - xi(2,1)]
[                                        ]
[xi(3,2)  xi(4,2)   - xi(1,2)   - xi(2,2)]


is nilpotent.

     [xi(1,1)  xi(1,2)   xi(1,3)     xi(1,4)  ]
     [                                        ]
     [xi(2,1)  xi(2,2)   xi(1,4)     xi(2,4)  ]
m := [                                        ]
     [xi(3,1)  xi(3,2)   - xi(1,1)   - xi(2,1)]
     [                                        ]
     [xi(3,2)  xi(4,2)   - xi(1,2)   - xi(2,2)]


we may suppose that A is an element of sp(4,C)+, that is:

xi(1,1):=0

xi(2,1):=0

xi(2,2):=0

xi(3,1):=0

xi(3,2):=0

xi(4,2):=0

M**1:=

[0  xi(1,2)   xi(1,3)    xi(1,4)]
[                               ]
[0     0      xi(1,4)    xi(2,4)]
[                               ]
[0     0         0          0   ]
[                               ]
[0     0      - xi(1,2)     0   ]


M**2:=

[0  0          0           xi(2,4)*xi(1,2)]
[                                         ]
[0  0   - xi(2,4)*xi(1,2)         0       ]
[                                         ]
[0  0          0                  0       ]
[                                         ]
[0  0          0                  0       ]


M**3:=

[                        2   ]
[0  0   - xi(2,4)*xi(1,2)   0]
[                            ]
[0  0           0           0]
[                            ]
[0  0           0           0]
[                            ]
[0  0           0           0]


M**4:=

[0  0  0  0]
[          ]
[0  0  0  0]
[          ]
[0  0  0  0]
[          ]
[0  0  0  0]


Trace(M**1)/2:=0$

Trace(M**2)/2:=0$

Trace(M**3)/2:=0$

Trace(M**4)/2:=0$

************************************************************************$

*******Suppose xi(1,2) neq 0.$

************************************************************************$

By subtracting adjoints one then may suppose:$

xi(5,1):=0,xi(5,2):=0,xi(5,3):=0,xi(5,4):=0$

delta:=

[   0     xi(1,2)   xi(1,3)    xi(1,4)  0     0   ]
[                                                 ]
[   0        0      xi(1,4)    xi(2,4)  0     0   ]
[                                                 ]
[   0        0         0          0     0     0   ]
[                                                 ]
[   0        0      - xi(1,2)     0     0     0   ]
[                                                 ]
[   0        0         0          0     0  xi(5,6)]
[                                                 ]
[xi(6,1)  xi(6,2)   xi(6,3)    xi(6,4)  0     0   ]


We denote this delta by the shortform$

shortformdelta:={xi(1,2),
xi(1,3),
xi(1,4),
ss,
xi(2,4),
ss,
xi(5,6),
ss,
xi(6,1),
xi(6,2),
xi(6,3),
xi(6,4)}$

paramindexeslist:={{1,2},{1,3},{1,4},{2,4},{5,6},{6,1},{6,2},{6,3},{6,4}}$

a:=0$

b:=0$

delta:=

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


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

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

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

sa valeur doit etre WW:=0$

on resout l'equation {{0,1},5} qui est  maintenant AA:=d(6,1) - d(3,0)$

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

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

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

Unknown: d(3,2)
Unknown: d(3,2)
bonne inconnue W:=d(3,2)$

sa valeur doit etre WW:=0$

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

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

sa valeur doit etre WW:=d(4,0)$

on resout l'equation {{0,3},0} 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$

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

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

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

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

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

sa valeur doit etre WW:=0$

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

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

sa valeur doit etre WW:=0$

on resout l'equation {{0,3},5} qui est  maintenant AA:=d(6,3) - d(5,1) + d(1,0)$

Unknowns: {d(6,3),d(5,1),d(1,0)}
Unknowns: {d(6,3),d(5,1),d(1,0)}
bonne inconnue W:=d(6,3)$

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

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

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

sa valeur doit etre WW:=0$

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

Unknown: d(3,4)
Unknown: d(3,4)
bonne inconnue W:=d(3,4)$

sa valeur doit etre WW:=0$

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

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

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

on resout l'equation {{0,5},1} 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 {{0,5},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},1} qui est  maintenant AA:=d(3,6) - d(1,5)$

Unknowns: {d(3,6),d(1,5)}
Unknowns: {d(3,6),d(1,5)}
bonne inconnue W:=d(3,6)$

sa valeur doit etre WW:=d(1,5)$

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

Unknown: d(4,5)
Unknown: d(4,5)
bonne inconnue W:=d(4,5)$

sa valeur doit etre WW:=0$

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

Unknowns: {d(6,6),d(5,5),d(0,0)}
Unknowns: {d(6,6),d(5,5),d(0,0)}
bonne inconnue W:=d(6,6)$

sa valeur doit etre WW:=d(5,5) - d(0,0)$

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

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

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

on resout l'equation {{2,3},1} 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 {{2,3},5} qui est  maintenant AA:=d(4,3) + d(1,2)$

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

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

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

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

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

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

Unknown: d(4,6)
Unknown: d(4,6)
bonne inconnue W:=d(4,6)$

sa valeur doit etre WW:=0$

on resout l'equation {{3,4},1} 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 {{3,4},5} qui est  maintenant AA:=d(2,3) - d(1,4)$

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

sa valeur doit etre WW:=d(1,4)$

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

Unknown: d(0,6)
Unknown: d(0,6)
bonne inconnue W:=d(0,6)$

sa valeur doit etre WW:=0$

on resout l'equation {{3,6},5} qui est  maintenant AA:= - d(1,6) + d(0,3)$

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

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

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

Unknown: d(2,6)
Unknown: d(2,6)
bonne inconnue W:=d(2,6)$

sa valeur doit etre WW:=0$

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

pour delta:=

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


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

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

dim Der(gtildedelta):=19$

t1:=D(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  -1  0   0   0 ]
[                       ]
[0  0  0  0   -1  0   0 ]
[                       ]
[0  0  0  0   0   -1  0 ]
[                       ]
[0  0  0  0   0   0   -2]


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

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

commutant de t1 dans der(gtildedelta):

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

    (0,d(1,1),d(1,2),0,0,0,0),

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

    (0,0,0,d(1,1) - d(0,0),0,0,0),

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

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

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


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

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

t2:=D(1,1):=

[0  0  0  0  0  0  0]
[                   ]
[0  1  0  0  0  0  0]
[                   ]
[0  0  0  0  0  0  0]
[                   ]
[0  0  0  1  0  0  0]
[                   ]
[0  0  0  0  2  0  0]
[                   ]
[0  0  0  0  0  2  0]
[                   ]
[0  0  0  0  0  0  2]


Unknowns: {d(5,4),d(2,2),d(1,1),d(0,0)}
Unknowns: {d(5,4),d(2,2),d(1,1),d(0,0)}
commutant simultane de t1,t2 dans der(gtildedelta):$

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

Unknowns: {d(5,4),d(2,2),d(1,1),d(0,0)}

Unknowns: {d(5,4),d(2,2),d(1,1),d(0,0)}

t3:=D(2,2):=

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


Unknowns: {d(2,2),d(1,1),d(0,0)}

Unknowns: {d(2,2),d(1,1),d(0,0)}

commutant simultane de t1,t2,t3 dans der(gtildedelta):

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

    (0,d(1,1),0,0,0,0,0),

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

    (0,0,0,d(1,1) - d(0,0),0,0,0),

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

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

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


rank 3 with maximal torus t1,t2,t3

3


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 ]
[                       ]
[0  0  0  0   0   0   0 ]
[                       ]
[0  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  0 ]
[                       ]
[0  0  0  0   0   0   -2]

P**(-1)*t2*P:=

[0  0  0  0  0  0  0]
[                   ]
[0  1  0  0  0  0  0]
[                   ]
[0  0  0  0  0  0  0]
[                   ]
[0  0  0  1  0  0  0]
[                   ]
[0  0  0  0  2  0  0]
[                   ]
[0  0  0  0  0  2  0]
[                   ]
[0  0  0  0  0  0  2]

P**(-1)*t3*P:=

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


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

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

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,d(0,3),0,0,0),

    (d(1,0),d(1,1),d(1,2),d(1,3),d(1,4),0,d(0,3)),

    (d(2,0),0,d(2,2),d(1,4),d(2,4),0,0),

    (0,0,0,d(1,1) - d(0,0),0,0,0),

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

    (d(5,0),d(5,1),d(5,2),d(5,3),d(5,4),2*d(1,1) - d(0,0),d(5,6)),

    (d(6,0),0,d(4,0),d(5,1) - d(1,0), - d(2,0),0,2*(d(1,1) - d(0,0))))


on voit apparaitre les poids sur la diagonale

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

r(2) := d(1,1)

r(3) := d(2,2)

r(4) := d(1,1) - d(0,0)

r(5) :=  - d(2,2) + 2*d(1,1) - d(0,0)

r(6) := 2*d(1,1) - d(0,0)

r(7) := 2*(d(1,1) - d(0,0))

r(1) := gamma2

r(2) := gamma1 + gamma2

r(3) := gamma2 - gamma3 + 2*gamma1

r(4) := gamma1

r(5) := gamma3

r(6) := 2*gamma1 + gamma2

r(7) := 2*gamma1

Le systeme de poids est le systeme 3.18

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

listcommutateursdesx := {{{0,1},0},

   {{0,2},0},

   {{0,3},x(1)},

   {{0,4},0},

   {{0,5},0},

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

   {{1,2},0},

   {{1,3},x(5)},

   {{1,4},0},

   {{1,5},0},

   {{1,6},0},

   {{2,3},0},

   {{2,4},x(5)},

   {{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},0},
{{1,3},0},
{{1,4},diay(2)},
{{1,5},0},
{{1,6},0},
{{1,7},diay(6)},
{{2,3},0},
{{2,4},diay(6)},
{{2,5},0},
{{2,6},0},
{{2,7},0},
{{3,4},0},
{{3,5},diay(6)},
{{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_{7,3.18}$

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

det(isom):= 1$

ZZ(1):=diay(4)$

ZZ(2):=diay(1)$

ZZ(3):=diay(5)$

ZZ(4):= - diay(3)$

ZZ(5):=diay(7)$

ZZ(6):= - diay(2)$

ZZ(7):=diay(6)$

listcommutateursdesZZ:=$

{{1,2},zz(6)}$

{{1,3},0}$

{{1,4},0}$

{{1,5},0}$

{{1,6},zz(7)}$

{{1,7},0}$

{{2,3},0}$

{{2,4},0}$

{{2,5},zz(7)}$

{{2,6},0}$

{{2,7},0}$

{{3,4},zz(7)}$

{{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_{7,3.18}$

Et cela pour a:=0, b:=0.$

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

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

The isomorphism from g_{7,3.18} to gtildedelta$

was constructed in 2 steps and is given by$

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

which we record here under the name PSI$