%% Builtin Aggregates in LDL++

% Schema
%-------
database({father(Name:string, Children:any),
	  mother(Name:string, Children:any)
	 }).

%Derivated predicates and rules
%------------------------------
%list the number of children for each father
no_of_children(X, No) <- father(X, C_Set),
			 aggr(count, C_Set, No).

export father(X, S).
export father($X, S).
export mother(X, S).
export mother($X, S).
export no_of_children(X, Y).
export no_of_children($X, Y).