The child is walking through straw.
The child is sitting on a bed.
One cannot be walking through straw and sitting on a bed at the same time.
exists e1 x1 x2.(n_child(x1) & through(e1,x2) & n_straw(x2) & Actor(e1,x1) & v_walk(e1))
exists e1 x1 x2.(n_child(x1) & on(e1,x2) & n_bed(x2) & Actor(e1,x1) & v_sit(e1))