A surfer riding a big wave.
There are no waves
If there are no waves, the surfer cannot be riding a big wave.
exists e1 s1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_wave(x3) & a_big(s1) & Theme(s1,x3) & (x1 = x2) & n_surfer(x1))
exists p1 x1.-exists x2.((x1 = x2) & n_wave(x2))