% What is known about sore joints
background([ [sore_elbow(X), tennis_elbow(X)],
             [sore_elbow(X), sore_joints(X)],
             [sore_joints(X), arthritis(X)],
             [sore_hips(X), sore_joints(X)],
             [sore_hips(X), hip_fracture(X)],
             [tennis_player(X), tennis_elbow(X)] ]).

% The possible explanations to consider
assumable(tennis_elbow(_)).
assumable(arthritis(_)).
