Two children in hats play in an open, rocky field.
The children are playing catch.
The first sentence does not specify what, exactly, they are playing.  It may not be catch.
exists e1 s1 s2 s3 x1 x2 x3.(in(e1,x3) & n_field(x3) & a_rocky(s3) & Theme(s3,x3) & a_,(s2) & Theme(s2,x3) & a_open(s1) & Theme(s1,x3) & Actor(e1,x1) & v_play(e1) & in(x1,x2) & n_hat(x2) & n_child(x1) & card_eq_2(x1))
exists e1 x1 x2.(n_child(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_catch(x2))