A guy on a snowboard grinding.
There is a person on sports equipment.
A snowboard would be considered sports equipment.
exists e1 x1 x2 x3.(a_topic(x1) & on(x1,x2) & Actor(e1,x3) & v_grind(e1) & (x2 = x3) & n_snowboard(x2) & n_guy(x1))
exists p1 x1 x2 x3 x4.((x1 = x2) & on(x2,x3) & n_equipment(x3) & of(x3,x4) & n_sport(x4) & n_person(x2))