People sit on a bench by the pool.
People are sitting.
People sit on a bench so they are sitting.
exists e1 x1 x2 x3.(n_pool(x3) & by(e1,x3) & on(e1,x2) & n_bench(x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1))
exists e1 x1.(Actor(e1,x1) & v_sit(e1) & n_people(x1))