People wearing hats are gathered outside on a sunny day.
people are at the park for a picknic
People at a park may or may not be wearing hats and the day may not be sunny.
exists e1 e2 s1 s2 x1 x2 x3 x4.(on(e2,x4) & n_day(x4) & a_sunny(s2) & Theme(s2,x4) & a_outside(s1) & Manner(e2,s1) & Theme(e2,x1) & v_gather(e2) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_hat(x3) & (x1 = x2) & n_people(x1))
exists p1 x1 x2.(n_park(x2) & exists x3.(at(x1,x2) & for(x2,x3) & n_picknic(x3)) & n_people(x1))