FUNCTION: IshA - test whether the argument is a product of elements of the h-basis on a formal alphabet expression

CALLING SEQUENCE:

IshA(expr)

TYP[IshA](expr)

PARAMETERS:

expr = any expression

SYNOPSIS:

• The IshA function tests whether the argument expr is a product of elements of the h-basis on a formal alphabet expression, that is h[part](alphab), where part denotes a partition in non-increasing order and alphab is a valid formal alphabet expression.

• Allowed alphabet expressions are linear combinations of formal alphabets A1, A2, etc.

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

EXAMPLES:

> with(TYP):
> IshA( h[](A1-A2) );
 
                                     true
 
> IshA( h[3,3,1](2/3*A3) );
 
                                     true