A dog swims toward a stick
a dog is not swimming
A dog swims or is not swimming.  different action
exists e1 x1 x2.(toward(e1,x2) & n_stick(x2) & Actor(e1,x1) & v_swim(e1) & n_dog(x1))
exists x1.(-exists e1.(Actor(e1,x1) & v_swim(e1)) & n_dog(x1))