The people are very crowded in the plaza.
the plaza is empty
The plaza cannot be empty if it is crowded with people.
exists s1 x1 x2.(n_plaza(x2) & n_people(x1) & r_very(s1) & in(s1,x2) & Theme(s1,x1) & a_crowd(s1))
exists s1 x1.(n_plaza(x1) & Theme(s1,x1) & a_empty(s1))