FUNCTION: SgaMinus - difference of two elements of the symmetric group algebra

CALLING SEQUENCE:

SgaMinus(e_1, e_2)

SGA[SgaMinus](e_1, e_2)

PARAMETERS:

e_1, e_2 = any elements of the symmetric group algebra

SYNOPSIS:

• The SgaMinus function computes the difference between two elements of the symmetric group algebra.

• One can use instead the operator &!-.

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

EXAMPLES:

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