?-
project(suppliers,[sno],t71),
rename(t71,[sx],t72),
rename(t71,[sy],t73),
times(t72,t73,t74),
%
project(spj,[sno,pno],u71),
rename(u71,[sx,p],u72),
%
project(spj,[pno],v71),
rename(v71,[p],v72),
times(t73,v72,v73),
rename(u71,[sy,p],v74),
minus(v73,v74,v75),
join(t73,v75,v76),
join(u72,v76,v77),
project(v77,[sx,sy],v78),
minus(t74,v78,v79),
%
times(t72,v72,w71),
minus(w71,u72,w72),
join(w72,t72,w73),
join(w73,v74,w74),
project(w74,[sx,sy],w75),
%
minus(v79,w75,r71),
select(r71,[[sx,'<',sy]],r72),
displayRelation(r72).