A man sitting down talking on a cellphone.
A man is on the cellphone
Just because a man in on  a cellphone doesn't mean he is talking on it.
exists e2 e1 s1 x1 x2 x3.(a_topic(x1) & for(e1,e2) & on(e2,x3) & n_cellphone(x3) & Actor(e2,x2) & v_talk(e2) & a_down(s1) & Manner(e1,s1) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_man(x1))
exists p1 x1 x2.(n_cellphone(x2) & on(x1,x2) & n_man(x1))