A large group of people waiting at a train station.
A group of schoolchildren going on a fieldtrip are waiting to board a train.
A group does not have to be large.  People do not have to be schoolchildren.  People do not have to be waiting to board a train at a train station.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & of(x1,x2) & at(e1,x4) & n_station(x4) & of(x4,x5) & n_train(x5) & Actor(e1,x3) & v_wait(e1) & (x2 = x3) & n_people(x2) & n_group(x1) & a_large(s1) & Theme(s1,x1))
exists e1 e2 p1 x1 x2 x3 x4.(Topic(e2,p1) & Actor(e2,x1) & v_wait(e2) & exists e3 x5.(Theme(e3,x5) & Actor(e3,x1) & v_board(e3) & n_train(x5)) & on(e1,x4) & n_fieldtrip(x4) & Actor(e1,x3) & v_go(e1) & (x1 = x3) & of(x1,x2) & n_schoolchildren(x2) & n_group(x1))