People are outside at night.
Some people are outside.
Some people are people, and outside at night implies outside.
exists s1 x1 x2.(at(s1,x2) & n_night(x2) & Theme(s1,x1) & a_outside(s1) & n_people(x1))
exists s1 x1.(Theme(s1,x1) & a_outside(s1) & n_people(x1))