A boy surfs on a wave.
The ocean is cold.
A boy surfing on a wave doesn't necessarily imply that he is surfing in an ocean.
exists e1 x1 x2.(on(e1,x2) & n_wave(x2) & Actor(e1,x1) & v_surf(e1) & n_boy(x1))
exists s1 x1.(n_ocean(x1) & Theme(s1,x1) & a_cold(s1))