Four friends engaged in conversation.
group discussion
four friends were engaged in group discussion
exists e1 x1 x2.(in(e1,x2) & n_conversation(x2) & Theme(e1,x1) & v_engage(e1) & n_friend(x1) & card_eq_4(x1))
exists x1 x2.(n_discussion(x1) & of(x1,x2) & n_group(x2) & a_topic(x1))