A person on a green board is snowboarding in midair.
The board is blue.
The subject is different because it can't be blue and green at the same time.
exists e1 s1 x1 x2 x3.(in(e1,x3) & n_midair(x3) & Actor(e1,x1) & v_snowboard(e1) & on(x1,x2) & n_board(x2) & a_green(s1) & Theme(s1,x2) & n_person(x1))
exists s1 x1.(n_board(x1) & Theme(s1,x1) & a_blue(s1))