A man in a bar.
A woman in a bar.
Implies a man and woman is in a bar which means that it isn't just a person.
exists x1 x2.(a_topic(x1) & in(x1,x2) & n_bar(x2) & n_man(x1))
exists x1 x2.(a_topic(x1) & in(x1,x2) & n_bar(x2) & n_woman(x1))