module m3.
%W. Nauber 30.05.05

type r, w, s o.

w:-s.
r.

module m2.
import m3.

type p o.

p:-w.


module m1.
import m2.

type q o.

q:-p.
s:-r.

%#query m1.
%goal q succieds:
%?- spy _ q.
%Solving goal: q
%Solving goal: p
%Solving goal: w
%Solving goal: s
%Solving goal: r
%Solving goal: true

%solved

%?- spy _ s.
%Solving goal: s
%Solving goal: r

%no