%------------------------------------------------------------------------
% Program for which everything is undefined.
%------------------------------------------------------------------------

:- table p/0, q/0, r/0.

p :- tnot(q).
p :- tnot(r).

q :- p.

r :- p.

%------------------------------------------------------------------------

test :- p, fail.
test :-
        ( p ->
	    ( tnot(p) -> writeln('p is undefined (OK)') ; writeln('p is true') )
	; writeln('p is false') ),
        ( q ->
	    ( tnot(q) -> writeln('q is undefined (OK)') ; writeln('q is true') )
	; writeln('q is false') ),
        ( r ->
	    ( tnot(r) -> writeln('r is undefined (OK)') ; writeln('r is true') )
	; writeln('r is false') ).