FUNCTION: NcaMinus - difference of two elements of the nilCoxeter algebra

CALLING SEQUENCE:

NcaMinus(e_1, e_2)

NCA[NcaMinus](e_1, e_2)

PARAMETERS:

e_1, e_2 = any elements of the nilCoxeter algebra

SYNOPSIS:

• The NcaMinus function computes the difference between two elements of the nilCoxeter algebra.

• One can use instead the operator &@-.

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

EXAMPLES:

> with(NCA):
> a:=q + u/t*A[3,1,2]:
> b:=t - A[1,3,2]:
> NcaMinus(a, b);
 
                                     u A[3, 1, 2]
                (q - t) A[1, 2, 3] + ------------ + A[1, 3, 2]
                                           t
 
> a &@- a;
 
                                       0