A skateboarder is balancing on the rail of stairs.
A hyper skateboarder is balancing on the rail of stairs.
Not all skateboarders are hyper.
exists e1 x1 x2 x3.(n_rail(x2) & on(e1,x2) & of(x2,x3) & n_stair(x3) & Actor(e1,x1) & v_balance(e1) & n_skateboarder(x1))
exists e1 x1 x2 x3 x4.(n_rail(x3) & on(e1,x3) & of(x3,x4) & n_stair(x4) & Actor(e1,x1) & v_balance(e1) & n_skateboarder(x1) & of(x1,x2) & n_hyper(x2))