Hundreds of people gathered at an event.
Hundreds of happy people are gathered
The fact that people are gathered at an event doesn't mean they are happy, it could be a memorial service.
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 e1 s1 x1 x2.(Theme(e1,x1) & v_gather(e1) & of(x1,x2) & n_people(x2) & a_happy(s1) & Theme(s1,x2) & n_hundred(x1))