FUNCTION: Rd2Nca - calculate a product of generators

CALLING SEQUENCE:

Rd2Nca(rd)

Rd2Nca(rd, n)

NCA[Rd2Nca](rd)

NCA[Rd2Nca](rd, n)

PARAMETERS:

rd = any list denoting a decomposition

n = any positive integer denoting the degree of a symmetric group

SYNOPSIS:

• The Rd2Nca function calculates the product of the generators given by the decomposition rd. The product is taken in the nilCoxeter algebra.

• If rd is reduced then Rd2Nca(rd)=SG['Rd2Perm'](rd), and 0 otherwise.

• When the second argument is not present, n is the smallest possible degree.

• Whenever there is a conflict between the function name Rd2Nca and another name used in the same session, use the long form NCA['Rd2Nca'].

EXAMPLES:

> with(NCA):
> Rd2Nca([1,2,1], 5);
 
                                 A[3, 2, 1, 4, 5]
 
> Rd2Nca([1,2,1]);
 
                                    A[3, 2, 1]
 
> Rd2Nca([1,2,1,2]);
 
                                         0