Four children in the pool.
Some childrens in the swimming pool
The children could be in a wading pool and not a swimming pool.
exists x1 x2.(n_pool(x2) & a_topic(x1) & in(x1,x2) & n_child(x1) & card_eq_4(x1))
exists x1 x2 x3.(n_pool(x2) & of(x2,x3) & n_swimming(x3) & a_topic(x1) & in(x1,x2) & n_children(x1))