Young women and men sitting together on a stairway.
An old lady walks down the stairway.
Young women and men are not the same as one old lady.  Walking and sitting are different.
exists e1 s1 s2 s3 x1 x2 x3 x4.(a_topic(s1) & on(e1,x4) & n_stairway(x4) & a_together(s3) & Manner(e1,s3) & Actor(e1,x3) & v_sit(e1) & (s1 = x3) & n_man(x2) & n_woman(x1) & subset_of(x2,s1) & subset_of(x1,s1) & a_young(s2) & Theme(s2,s1))
exists e1 s1 s2 x1 x2.(n_stairway(x2) & a_down(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_lady(x1) & a_old(s1) & Theme(s1,x1))