People are gathered at an event in the city.
The event is busy.
Just because people are gathered does not mean the event is particularly busy.
exists e1 x1 x2 x3.(n_city(x3) & at(e1,x2) & in(x2,x3) & n_event(x2) & Theme(e1,x1) & v_gather(e1) & n_people(x1))
exists s1 x1.(n_event(x1) & Theme(s1,x1) & a_busy(s1))