FUNCTION: Rd2Perm - calculate a permutation from a decomposition

CALLING SEQUENCE:

Rd2Perm(rd)

Rd2Perm(rd, n)

SG[Rd2Perm](rd)

SG[Rd2Perm](rd, n)

PARAMETERS:

rd = any list denoting a decomposition

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

SYNOPSIS:

• The Rd2Perm function calculates the permutation corresponding to the list rd, the entries of rd being interpreted as simple transpositions. Let rd=[i,j,k,...], then Rd2Perm(rd)=MultPerm(s_i, s_j, s_k, ...) where s_i stands for SgTranspo(i, n).

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

• The decomposition needs not to be reduced.

• Whenever there is a conflict between the function name Rd2Perm and another name used in the same session, use the long form SG['Rd2Perm'].

EXAMPLES:

> with(SG):
> Rd2Perm([1,2,1], 5);
 
                                  [3, 2, 1, 4, 5]
 
> Rd2Perm([1,2,1]);
 
                                    [3, 2, 1]