HELP FOR: how Schubert polynomials are represented in ACE

SYNOPSIS:

• This part describes how (double) Schubert polynomials are represented in ACE.

• Schubert polynomials may be indexed by permutations or integer vectors. In the first case, they are denoted by the expression X[permutation] and in the second one, by Y[code] where code is a sequence of non- negative integers (interpreted as the code of a permutation).

• In the case of double Schubert polynomials we denote by XX[permutation] the double Schubert polynomial indexed by a permutation and by YY[code] the corresponding double Schubert polynomial indexed by a vector of non-negative integers (interpreted as the code of a permutation).

EXAMPLES:

> with(TYP):
> IsXX(XX[3,1,2,4]);
 
                                   true