FUNCTION: Perm2ListRd - list all reduced decompositions of a given permutation

CALLING SEQUENCE:

Perm2ListRd(perm)

SG[Perm2ListRd](perm)

PARAMETERS:

perm = any list denoting a permutation

SYNOPSIS:

• The Perm2ListRd function returns the list of all reduced decompositions of a given permutation, i.e. all expressions of perm as a product (of minimal length) of simple transpositions.

• When used with the second parameter 'nb', it returns the number of such decompositions.

• Whenever there is a conflict between the function name Perm2ListRd and another name used in the same session, use the long form SG['Perm2ListRd'].

EXAMPLES:

> with(SG):
> Perm2ListRd([3,1,5,2,4]);
 
   [[4, 2, 3, 1], [2, 4, 3, 1], [4, 2, 1, 3], [2, 4, 1, 3], [2, 1, 4, 3]]
 
> Perm2ListRd([6,5,4,3,2,1], 'nb');
 
                                 292864