A family playing in the pool.
A family is swimming in their pool.
Not all playing means swimming in a pool.
exists x1 x2 x3.(n_pool(x3) & a_topic(x1) & in(x1,x3) & n_playing(x1) & of(x1,x2) & n_family(x2))
exists e1 x1 x2.(in(e1,x2) & n_pool(x2) & of(x2,x1) & n_thing(x1) & Actor(e1,x1) & v_swim(e1) & n_family(x1))