The students are practicing martial arts.
The students are on a tire swing
The students practicing martial arts cannot be on a tire swing.
exists e1 s1 x1 x2.(n_student(x1) & Theme(e1,x2) & Actor(e1,x1) & v_practice(e1) & n_art(x2) & a_martial(s1) & Theme(s1,x2))
exists p1 x1.(n_student(x1) & exists x2 x3.(on(x1,x2) & n_swing(x2) & of(x2,x3) & n_tire(x3)))