A man speaking at a conference.
The man is speaking.
If someone is speaking at a conference then they must actually be speaking.
exists x1 x2 x3.(a_topic(x1) & at(x1,x3) & n_conference(x3) & n_speaking(x1) & of(x1,x2) & n_man(x2))
exists e1 x1.(n_man(x1) & Actor(e1,x1) & v_speak(e1))