A boy climbs rocks.
A girl is swinging on a swingset.
Subject could be either a boy or girl.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_climb(e1) & n_rock(x2) & n_boy(x1))
exists e1 x1 x2.(on(e1,x2) & n_swingset(x2) & Actor(e1,x1) & v_swing(e1) & n_girl(x1))