A man is skateboarding at a park.
A person is skateboarding at a park.
A man is a person! That can definitely be inferred.
exists e1 x1 x2.(at(e1,x2) & n_park(x2) & Actor(e1,x1) & v_skateboard(e1) & n_man(x1))
exists e1 x1 x2.(at(e1,x2) & n_park(x2) & Actor(e1,x1) & v_skateboard(e1) & n_person(x1))