A girl jumps while dancing on stage.
The girl is a gymnast.
Not all girls are a gymnast.
exists e2 e1 x1 x2.(while(e1,e2) & on(e2,x2) & n_stage(x2) & Actor(e2,x1) & v_dance(e2) & Actor(e1,x1) & v_jump(e1) & n_girl(x1))
exists p1 x1.(n_girl(x1) & exists x2.((x1 = x2) & n_gymnast(x2)))