The dogs are walking in the desert.
The dogs are running in the desert.
Dogs cannot be walking and running simultaneously.
exists e1 x1 x2.(n_desert(x2) & n_dog(x1) & in(e1,x2) & Actor(e1,x1) & v_walk(e1))
exists e1 x1 x2.(n_desert(x2) & n_dog(x1) & in(e1,x2) & Actor(e1,x1) & v_run(e1))