Maxima Function
contract (psym, lvar)
returns a contracted form (i.e. a monomial orbit under the action of the
symmetric group) of the polynomial psym in the variables contained
in the list lvar. The function explose performs the
inverse operation. The function tcontract tests the symmetry of
the polynomial.
(%i1) psym: explose (2*a^3*b*x^4*y, [x, y, z]); 3 4 3 4 3 4 3 4 (%o1) 2 a b y z + 2 a b x z + 2 a b y z + 2 a b x z 3 4 3 4 + 2 a b x y + 2 a b x y (%i2) contract (psym, [x, y, z]); 3 4 (%o2) 2 a b x y