People in the street celebrating something.
The people are celebrating a holiday.
What they are celebrating is not necessarily a holiday.
exists e1 x1 x2 x3 x4.(n_street(x2) & a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_celebrate(e1) & n_thing(x4) & (x1 = x3) & in(x1,x2) & n_people(x1))
exists e1 x1 x2.(n_people(x1) & Theme(e1,x2) & Actor(e1,x1) & v_celebrate(e1) & n_holiday(x2))