state(X) :- 
	hasP(X,_);
	sovereignState(X).
people(Y) :- hasP(_,Y).

sovereignState(X) :-
	hasS(X,_);
	nationState(X).
sovereignty(Y) :- 
	hasS(_,Y);
	via(Y,_);
	politicalSovereignty(Y);
	economicSovereignty(Y).
system(X) :-
	via(_,X);
	politicalSystem(X);
	religiousSystem(X);
	economicSystem(X).

%classification rule
nationState(X) :-
	hasS(X,Y),
	politicalSovereignty(Y).

hasP(canada,p2).
%the next 2 lines are unnecessary. Why?
state(canada).
people(p2).
hasS(canada,s2).
% sovereignState(canada). should be Yes
politicalSovereignty(s2).
% nationState(canada) should be Yes

hasP(us,p1). 
% state(us) should be Yes
% people(p1) should be Yes
hasS(us,s1).
% sovereignState(us). should be Yes
% nationState(us). should be NO
:- unknown(_, fail).