FUNCTION: BnaMinus - difference of two elements of any Bn-algebra

CALLING SEQUENCE:

BnaMinus(e_1, e_2)

BNA[BnaMinus](e_1, e_2)

PARAMETERS:

e_1, e_2 = any elements of any Bn-algebra

SYNOPSIS:

• The BnaMinus function computes the difference between two elements of either the Bn-group algebra, Bn-nilCoxeter algebra or the Bn-idCoxeter algebra.

• One can use instead the operator &!!-.

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

EXAMPLES:

> with(BNA):
> a:=q + u/t*B[0,1,2]:
> b:=t - B[1,2,1]:
> BnaMinus(a, b);
 
                             u B[0, 1, 2]
                B[1, 2, 1] + ------------ + (q - t) B[0, 0, 0]
                                   t
 
> a &!!- a;
 
                                       0