The boy is cutting the grass.
The girl weed-eated the yard.
A boy is not a girl.
exists e1 x1 x2.(n_grass(x2) & n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_cut(e1))
exists e1 x1 x2.(n_yard(x2) & n_girl(x1) & Theme(e1,x2) & Actor(e1,x1) & v_weed-eat(e1))