Hundreds of people gathered at an event.
A large group of people at a concert.
Large is a relative term and may not well describe a group of hundreds of people if they are in a stadium that seats thousands.  An event does not necessarily mean a concert.
exists e1 x1 x2 x3.(at(e1,x3) & n_event(x3) & Actor(e1,x1) & v_gather(e1) & of(x1,x2) & n_people(x2) & n_hundred(x1))
exists s1 x1 x2 x3.(a_topic(x1) & of(x1,x2) & at(x2,x3) & n_concert(x3) & n_people(x2) & n_group(x1) & a_large(s1) & Theme(s1,x1))