%Facts
%-----
% for ancestor
parent(mary, marc).
parent(john, mary).
parent(tom, john).

% for graph algorithms
g('a', 'b', 3).
g('a', 'c', 2).
g('b', 'd', 2).
g('b', 'e', 3).
g('c', 'd', 4).
g('c', 'f', 3).
g('d', 'f', 2).
g('e', 'f', 1).