People outside in a city field.
Some people are having a picnic in a field.
Just because people are outside does not mean they are having a picnic.
exists x1 x2 x3 x4.(a_topic(x1) & in(x2,x3) & n_field(x3) & of(x3,x4) & n_city(x4) & outside(x1,x2) & n_thing(x2) & n_people(x1))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & in(x2,x3) & n_field(x3) & n_picnic(x2) & n_people(x1))