Two women laugh while sitting on the floor.
The women are sisters.
Not all women are sisters.
exists e1 e2 x1 x2.(n_floor(x2) & while(e1,e2) & on(e2,x2) & Actor(e2,x1) & v_sit(e2) & Actor(e1,x1) & v_laugh(e1) & n_woman(x1) & card_eq_2(x1))
exists p1 x1.(n_woman(x1) & exists x2.((x1 = x2) & n_sister(x2)))