query(p84,m,[m,a,b,c,d,r(a)],[a,c],[]).
%-----------------------------------------------------------

:- table a / 0.
:- table b / 0.
:- table c / 0.
:- table d / 0.
:- table m / 0.
:- table r / 1.

m :- c, tnot(a), tnot(r(_A)).
c :- b.
c.
b :- c, d.
a :- tnot(b).
d :- fail.
r(_A) :- fail.