An old man looks at people shopping.
An old man is shopping and watching people.
If a man looks at people shopping, it doesn't necessarily mean that he himself is shopping.
exists e1 s1 x1 x2.(r_shopping(e1) & at(e1,x2) & n_people(x2) & Actor(e1,x1) & v_look(e1) & n_man(x1) & a_old(s1) & Theme(s1,x1))
exists p1 s1 x1.(exists e1 x2 x3 x4 x5.((x1 = x2) & subset_of(e1,x2) & Theme(e1,x5) & Actor(e1,x4) & v_watch(e1) & n_people(x5) & n_thing(x4) & subset_of(x3,x2) & n_shopping(x3)) & n_man(x1) & a_old(s1) & Theme(s1,x1))