%% Database updates --- insertion/deletion
% Schema
%-------
database({city(Name:string, State:string, Population:integer),
	  distance(City1:string, City2:string, Distance:real)
	 }).

%Derivated predicates and rules
%------------------------------
delete_small_cities(Size) <- 
	city(Name, State, Population),
	Population < Size,
	-city(Name, State, Population).

city_q(N, S, P) <- city(N, S, P).

export delete_small_cities($Size).
export city_q(X,Y,Z).