coxeter2.4v.txt example

>    read `maple/coxeter2.4v.txt`;

coxeter and weyl 2.4v loaded.

Run 'withcoxeter()' or 'withweyl()' to use abbreviated names.

>    withcoxeter(); withweyl();

[exponents, interior_pt, cox_matrix, root_coords, orbit_size, induce, cartan_matrix, stab_chain, cox_number, vec2fc, diagram, base, cprod, index, class_size, multperm, orbit, reflect, co_base, num_refl...
[exponents, interior_pt, cox_matrix, root_coords, orbit_size, induce, cartan_matrix, stab_chain, cox_number, vec2fc, diagram, base, cprod, index, class_size, multperm, orbit, reflect, co_base, num_refl...
[exponents, interior_pt, cox_matrix, root_coords, orbit_size, induce, cartan_matrix, stab_chain, cox_number, vec2fc, diagram, base, cprod, index, class_size, multperm, orbit, reflect, co_base, num_refl...

Warning: new definition for  tensor

[tensor, weight_coords, co_rho, minuscule, branch, weight_mults, toM, toX, rho, weyl_dim, weight_sys, weights]

>    diagram(A4);

 

   1---2---3---4

 

>    diagram(F4);

 

   1---2=<=3---4

 

>    diagram(G2);

 

   1=<<=2

 

>    pos_roots(F4);

[-1/2*e1-1/2*e2-1/2*e3+1/2*e4, e1, e2-e1, e3-e2, 1/2*e1-1/2*e2-1/2*e3+1/2*e4, e2, e2+e1, -e1+e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, e4-e3, e1+e3, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e...
[-1/2*e1-1/2*e2-1/2*e3+1/2*e4, e1, e2-e1, e3-e2, 1/2*e1-1/2*e2-1/2*e3+1/2*e4, e2, e2+e1, -e1+e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, e4-e3, e1+e3, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e...
[-1/2*e1-1/2*e2-1/2*e3+1/2*e4, e1, e2-e1, e3-e2, 1/2*e1-1/2*e2-1/2*e3+1/2*e4, e2, e2+e1, -e1+e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, e4-e3, e1+e3, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e...

nops gives number of elements in a list. 24 positive roots implies the dim of F4 is 52.

>    nops(%);

24

weights gives fundamental weights

>    W := weights(F4);

W := [e4, 1/2*e1+1/2*e2+1/2*e3+3/2*e4, e2+e3+2*e4, e4+e3]

weyl_dim computes dim of irrep given heighest weight.

>    weyl_dim(W[1],F4);

26

weight_mults gives weights and their multiplicities within Weyl chamber

>    weight_mults(W[1],F4);

M[1,0,0,0]+2*M[0,0,0,0]

orbit gives orbit under Weyl group

>    o1 := orbit(W[1],F4);

o1 := [e4, 1/2*e1+1/2*e2+1/2*e3+1/2*e4, -1/2*e1+1/2*e2+1/2*e3+1/2*e4, 1/2*e1-1/2*e2+1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e4, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e2, 1/2*e...
o1 := [e4, 1/2*e1+1/2*e2+1/2*e3+1/2*e4, -1/2*e1+1/2*e2+1/2*e3+1/2*e4, 1/2*e1-1/2*e2+1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e4, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e2, 1/2*e...
o1 := [e4, 1/2*e1+1/2*e2+1/2*e3+1/2*e4, -1/2*e1+1/2*e2+1/2*e3+1/2*e4, 1/2*e1-1/2*e2+1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e4, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e2, 1/2*e...
o1 := [e4, 1/2*e1+1/2*e2+1/2*e3+1/2*e4, -1/2*e1+1/2*e2+1/2*e3+1/2*e4, 1/2*e1-1/2*e2+1/2*e3+1/2*e4, -1/2*e1-1/2*e2+1/2*e3+1/2*e4, 1/2*e1+1/2*e2-1/2*e3+1/2*e4, e3, -1/2*e1+1/2*e2-1/2*e3+1/2*e4, e2, 1/2*e...

X[a,b,c,d] represents character of irrep with highest weight a,b,c,d w.r.t. fundmental weights.

tensor gives tensor product:

>    tensor(W[1],W[1],F4);

X[2,0,0,0]+X[0,1,0,0]+X[0,0,0,1]+X[1,0,0,0]+X[0,0,0,0]

same thing can be done with toX (cp with tos in symmetric function package.)

>    toX(X[1,0,0,0]*X[1,0,0,0],F4);

X[2,0,0,0]+X[0,1,0,0]+X[0,0,0,1]+X[1,0,0,0]+X[0,0,0,0]

toM is same as weight_mults. cp with tom in symmetric functions package.

>    toM(X[2,0,0,0],F4);

M[2,0,0,0]+M[0,1,0,0]+3*M[0,0,0,1]+5*M[1,0,0,0]+12*M[0,0,0,0]

>