FUNCTION: IsA - test whether the argument is a basis element of an algebra related to the symmetric group

CALLING SEQUENCE:

IsA(expr)

TYP[IsA](expr)

PARAMETERS:

expr = any expression

SYNOPSIS:

• The IsA function tests whether expr is an indexed name coding an element of the basis of an algebra related to the symmetric group. This element must be indexed by a permutation.

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

EXAMPLES:

> with(TYP):
> IsA(A[3,1]);
 
                                false
 
> IsA(A[3,1,2]);
 
                                 true