A man pushing a cart near the subway.
A man is walking by.
A man walking by is presumably not pushing a cart, he is unoccupied.
exists e1 x1 x2 x3 x4.(n_subway(x4) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_push(e1) & near(x3,x4) & n_cart(x3) & (x1 = x2) & n_man(x1))
exists e1 s1 x1.(a_by(s1) & Manner(e1,s1) & Actor(e1,x1) & v_walk(e1) & n_man(x1))