An surfer airborne over a wave.
Two surfers crash into each other because there were no waves.
A surfer and two surfers are two different amounts of surfers.  There cannot be a wave and no waves simultaneously.
exists x1 x2 x3.(a_topic(x1) & over(x1,x3) & n_wave(x3) & n_airborne(x1) & of(x1,x2) & n_surfer(x2))
exists e1 x1.(all x2.(n_other(x2) -> exists p1.(exists p2 x3.-exists x4.((x3 = x4) & n_wave(x4)) & because(e1,p1) & into(e1,x2))) & Actor(e1,x1) & v_crash(e1) & n_surfer(x1) & card_eq_2(x1))