A hotdog vendor looks sad.
A hotdog vendor is unhappy.
Often when we're unhappy it shows on our face. Being unhappy can be caused by or result in many negative emotions.
exists e1 p1 x1 x2.(exists s1.(Theme(s1,x1) & a_sad(s1)) & Topic(e1,p1) & Actor(e1,x1) & v_look(e1) & n_vendor(x1) & of(x1,x2) & n_hotdog(x2))
exists s1 x1 x2.(Theme(s1,x1) & a_unhappy(s1) & n_vendor(x1) & of(x1,x2) & n_hotdog(x2))