Dog chases ball in water.
The dog is chasing a squirrel.
The dog can't be chasing a squirrel while he chases a ball.
exists e1 x1 x2 x3.(ne_nam_dog(x1) & in(e1,x3) & n_water(x3) & Theme(e1,x2) & Actor(e1,x1) & v_chase(e1) & n_ball(x2))
exists e1 x1 x2.(n_dog(x1) & Theme(e1,x2) & Actor(e1,x1) & v_chase(e1) & n_squirrel(x2))