Woman waiting for the train.
No one is waiting for the train.
There cannot be a woman waiting for a train and no one waiting for a train.
exists e1 x1 x2.(n_train(x2) & ne_nam_woman(x1) & for(e1,x2) & Actor(e1,x1) & v_wait(e1))
exists x2.(n_train(x2) & -exists e1 x1.(for(e1,x2) & Actor(e1,x1) & v_wait(e1) & n_one(x1)))