Two people painting in a dirty room.
The people swam in the river.
If people swam in the river, they would not be painting in a dirty room.
exists e1 x1 x2 x3.(in(e1,x2) & n_room(x2) & of(x2,x3) & n_dirty(x3) & Actor(e1,x1) & v_painting(e1) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2.(n_river(x2) & n_people(x1) & in(e1,x2) & Actor(e1,x1) & v_swim(e1))