A group of friends socializing at a barbecue.
People are at a barbecue.
They are at a barbecue because they are socializing at a barbecue.
exists e1 x1 x2 x3 x4.(a_topic(x1) & at(e1,x4) & n_barbecue(x4) & Actor(e1,x3) & v_socialize(e1) & (x1 = x3) & of(x1,x2) & n_friend(x2) & n_group(x1))
exists p1 x1.(exists x2.(at(x1,x2) & n_barbecue(x2)) & n_people(x1))