The man is skateboarding.
A girl if roller skating.
A man isn't a girl.
exists e1 x1.(n_man(x1) & Actor(e1,x1) & v_skateboard(e1))
exists x1 x2 x3.(a_topic(x1) & if(x1,x2) & n_skating(x2) & of(x2,x3) & n_roller(x3) & n_girl(x1))