People outside in a field harvesting something.
people harvest potatoes
Harvesting something does not imply it is potatoes.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & Theme(e1,x5) & Actor(e1,x4) & v_harvest(e1) & n_thing(x5) & (x1 = x4) & in(x2,x3) & n_field(x3) & outside(x1,x2) & n_thing(x2) & n_people(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_harvest(e1) & n_potato(x2) & n_people(x1))