A surfer riding the wave.
A person learning to swim.
A surfer riding a wave isn't learning to swim.
exists e1 x1 x2 x3.(n_wave(x3) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & (x1 = x2) & n_surfer(x1))
exists e1 p1 x1 x2.(a_topic(x1) & Topic(e1,p1) & Actor(e1,x2) & v_learn(e1) & exists e2.(Actor(e2,x2) & v_swim(e2)) & (x1 = x2) & n_person(x1))