A older man in a black shirt sitting on a fire hydrant.
Nobody is sitting.
There is a man in a black shirt sitting so the statement nobody is sitting is false.
exists e1 s1 s2 x1 x2 x3 x4 x5.(a_topic(x1) & in(x1,x2) & on(e1,x4) & n_hydrant(x4) & of(x4,x5) & n_fire(x5) & Actor(e1,x3) & v_sit(e1) & (x2 = x3) & n_shirt(x2) & a_black(s2) & Theme(s2,x2) & n_man(x1) & r_more(s1) & a_older(s1) & Theme(s1,x1))
-exists e1 x1.(Actor(e1,x1) & v_sit(e1) & n_person(x1))