Two Asian martial artists work on their skills.
Two ninjas are sparring
Not all artists are ninjas.
exists e1 s1 s2 x1 x2.(on(e1,x2) & n_skill(x2) & of(x2,x1) & n_thing(x1) & Actor(e1,x1) & v_work(e1) & n_artist(x1) & a_martial(s2) & Theme(s2,x1) & a_asian(s1) & Theme(s1,x1) & card_eq_2(x1))
exists e1 x1.(Actor(e1,x1) & v_spar(e1) & n_ninja(x1) & card_eq_2(x1))