indepartment(X,Y) :-
					head(X,Y) ;
					employee(X,Y).

colleagues(X,Y) :-  head(X,Z),employee(Y,Z);
					head(Y,Z),employee(X,Z),
					not(X=Y).


component(X,Y) :- haspart(Y,X).
component(X,Y) :- haspart(Z,X) ,
				  component(Z,Y).

memberof(X,Y) :- (head(X,Y) ; employee(X,Y)) ; (component(Z,Y) , (head(X,Z) ; employee(X,Z))).