% Common shared database loaded by every deployment node.
% Holds the family relations used in the tutorial's local and distributed
% Prolog sections.

ancestor_descendant(X, Y) :- parent_child(X, Y).
ancestor_descendant(X, Z) :-
    parent_child(X, Y),
    ancestor_descendant(Y, Z).

parent_child(X, Y) :- mother_child(X, Y).
parent_child(X, Y) :- father_child(X, Y).

mother_child(trude, sally).

father_child(tom, sally).
father_child(tom, erica).
father_child(mike, tom).

% n2 is the richer isotope node.

deployment_node(n2).

mortal(X) :-
    human(X).

human(socrates).
human(X) :-
    rpc('https://n1.elfenbenstornet.se', human(X)).

ancestor(X, Y) :-
    ancestor_descendant(X, Y).

descendant(X, Y) :-
    ancestor_descendant(Y, X).

family_member(X) :-
    parent_child(X, _).
family_member(X) :-
    parent_child(_, X).