Four people are jumping from the top of a flight of stairs.
A group is in motion.
Four people are a group.
exists e1 x1 x2 x3 x4.(n_top(x2) & from(e1,x2) & of(x2,x3) & of(x3,x4) & n_stair(x4) & n_flight(x3) & Actor(e1,x1) & v_jump(e1) & n_people(x1) & card_eq_4(x1))
exists p1 x1.(exists x2.(in(x1,x2) & n_motion(x2)) & n_group(x1))