IsAlgebraElement( obj )
returns true if obj, which may be an object of
arbitrary type, is an algebra element, and false otherwise. The function
will signal an error if obj is an unbound variable.
gap> IsAlgebraElement( (1,2) );
false
gap> IsAlgebraElement( NullMat( 2, 2 ) );
true
gap> IsAlgebraElement( FreeAlgebra( Rationals, 1 ).1 );
true
GAP 3.4.4