somebody in the air on a board
There is a board in the air.
If somebody is on a board in the air, then the board itself must be in the air.
exists x1 x2 x3.(n_air(x2) & a_topic(x1) & in(x1,x2) & on(x2,x3) & n_board(x3) & n_person(x1))
exists p1 x1 x2.(n_air(x2) & in(p1,x2) & exists x3.((x1 = x3) & n_board(x3)))