People talking at an event in a park.
The poeple are in a group
People at an even in a park do not necessarily fit in a group.
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x4) & n_park(x4) & at(e1,x3) & n_event(x3) & Actor(e1,x2) & v_talk(e1) & (x1 = x2) & n_people(x1))
exists p1 x1.(n_poeple(x1) & exists x2.(in(x1,x2) & n_group(x2)))