Doctors perform surgery on a patient.
A man at a dentist appointment.
A surgery is not a dentis appointment.
exists e1 x1 x2 x3.(on(e1,x3) & n_patient(x3) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_surgery(x2) & n_doctor(x1))
exists x1 x2 x3.(a_topic(x1) & at(x1,x2) & n_appointment(x2) & of(x2,x3) & n_dentist(x3) & n_man(x1))