A street vendor eats lunch while watching over her fresh meat stand.
A street vendor is eating a ham sandwich on his lunch break.
Not all lunch is a ham sandwich.  If she is watching over her stand, she is not on a lunch break.  Her implies a girl, not his.
exists e1 e2 s1 x1 x2 x3 x4 x5.(while(e1,e2) & over(e2,x4) & n_stand(x4) & of(x4,x5) & n_meat(x5) & a_fresh(s1) & Theme(s1,x4) & of(x4,x1) & n_female(x1) & Actor(e2,x1) & v_watch(e2) & Theme(e1,x3) & Actor(e1,x1) & v_eat(e1) & n_lunch(x3) & n_vendor(x1) & of(x1,x2) & n_street(x2))
exists e1 x1 x2 x3 x4 x5 x6.(Theme(e1,x3) & Actor(e1,x1) & v_eat(e1) & on(x3,x5) & n_break(x5) & of(x5,x6) & n_lunch(x6) & of(x5,x1) & n_male(x1) & n_sandwich(x3) & of(x3,x4) & n_ham(x4) & n_vendor(x1) & of(x1,x2) & n_street(x2))