:- object(x,
implements(symdiffp)).
:- info([
author is 'Paulo Moura',
version is 1.0,
date is 1999/12/29,
comment is 'Symbolic differentiation and simplification of a variable.',
source is 'Example based on the Clocksin and Mellish Prolog book.']).
diff(1).
simplify(x).
:- end_object.
