A person wakeboarding in the water.
A man is wakeboarding.
You can not infer it is a man.
exists e1 x1 x2 x3.(n_water(x3) & a_topic(x1) & in(e1,x3) & Actor(e1,x2) & v_wakeboard(e1) & (x1 = x2) & n_person(x1))
exists e1 x1.(Actor(e1,x1) & v_wakeboard(e1) & n_man(x1))