four kids are crossing a river by stepping stones
A group of kids are playing where they aren't supposed to.
Just because the kids are crossing a river doesn't imply that they are playing, they could just simply be crossing.  The fact that they are crossing a river does not indicate that they are where they aren't supposed to be.
exists e2 e1 x1 x2 x3.(by(e1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_step(e2) & n_stone(x3) & Theme(e1,x2) & Actor(e1,x1) & v_cross(e1) & n_river(x2) & n_kid(x1) & card_eq_4(x1))
exists e1 x1 x2 x3.(-exists e3 e2.(Time(e3,x1) & Recipient(e3,e2) & Topic(e3,x2) & v_suppose(e3) & Actor(e2,x2) & v_to(e2)) & n_thing(x2) & Time(e1,x1) & Actor(e1,x2) & v_play(e1) & of(x2,x3) & n_kid(x3) & n_group(x2) & n_location(x1))