The students are practicing martial arts.
Their style is karate
Not all martial arts are karate.
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 s1 x1 x2.(n_style(x2) & of(x2,x1) & n_thing(x1) & Theme(s1,x2) & a_karate(s1))