A man with glasses is at the dentist.
A man with contact is waiting at the dentist.
Contact are not glasses. A man with contact cannot be wearing glasses simultaneously.
exists p1 x1 x2 x3.(n_dentist(x3) & at(x1,x3) & with(x1,x2) & n_glass(x2) & n_man(x1))
exists e1 x1 x2 x3.(n_dentist(x3) & at(e1,x3) & Actor(e1,x1) & v_wait(e1) & with(x1,x2) & n_contact(x2) & n_man(x1))