Children are eating various stuff at a park.
There is a picnic at a park.
Just because children are eating at a park does not mean they are having a picnic.
exists e1 s1 x1 x2 x3.(at(e1,x3) & n_park(x3) & Theme(e1,x2) & Actor(e1,x1) & v_eat(e1) & n_stuff(x2) & a_various(s1) & Theme(s1,x2) & n_child(x1))
exists p1 x1 x2 x3.((x1 = x2) & at(x2,x3) & n_park(x3) & n_picnic(x2))