A singer and guitarist performing.
Two people are performing.
A singer and guitarist are two people.
exists s1 x1 x2 x3.(a_topic(s1) & subset_of(x2,s1) & n_perform(x2) & of(x2,x3) & n_guitarist(x3) & subset_of(x1,s1) & n_singer(x1))
exists e1 x1.(Actor(e1,x1) & v_perform(e1) & n_people(x1) & card_eq_2(x1))