A white bird is flying over the surface of the water.
A raven is gliding over a river.
The white bird cannot be a raven.
exists e1 s1 x1 x2 x3.(n_water(x3) & n_surface(x2) & over(e1,x2) & of(x2,x3) & Actor(e1,x1) & v_fly(e1) & n_bird(x1) & a_white(s1) & Theme(s1,x1))
exists e1 x1 x2.(over(e1,x2) & n_river(x2) & Actor(e1,x1) & v_glide(e1) & n_raven(x1))