FUNCTION: FreeConcat - concatenation product in the free algebra

CALLING SEQUENCE:

FreeConcat(e_1, e_2)

FREE[FreeConcat](e_1, e_2)

PARAMETERS:

e_1, e_2 = any elements of the free algebra

SYNOPSIS:

• The FreeConcat function computes the concatenation product of two elements of the free algebra. The function normalizes the result, by essentially collecting coefficients.

• One can use instead the operator &~*.

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

EXAMPLES:

> with(FREE):
> a:=q + u/t*w[2,1,1]:
> b:=t - w[1,2,2]:
> FreeConcat(a, b);
 
                                              u w[2, 1, 1, 1, 2, 2]
      q t w[] + u w[2, 1, 1] - q w[1, 2, 2] - ---------------------
                                                        t
 
> a &~* b;
 
                                              u w[2, 1, 1, 1, 2, 2]
      q t w[] + u w[2, 1, 1] - q w[1, 2, 2] - ---------------------
                                                        t