People walking in the rain.
Men with umbrellas walking in the rain.
people in the rain need not have umbrellas.
exists e1 x1 x2 x3.(n_rain(x3) & a_topic(x1) & in(e1,x3) & Actor(e1,x2) & v_walk(e1) & (x1 = x2) & n_people(x1))
exists e1 x1 x2 x3 x4.(n_rain(x4) & a_topic(x1) & with(x1,x2) & in(e1,x4) & Actor(e1,x3) & v_walk(e1) & (x2 = x3) & n_umbrella(x2) & n_man(x1))