A child is looking at graffiti.
The old man looks at his clean wall.
The wall can't be clean and also have graffiti.
exists e1 x1 x2.(at(e1,x2) & n_graffitus(x2) & Actor(e1,x1) & v_look(e1) & n_child(x1))
exists e1 s1 s2 x1 x2.(n_wall(x2) & a_clean(s2) & Theme(s2,x2) & of(x2,x1) & n_male(x1) & n_man(x1) & a_old(s1) & Theme(s1,x1) & at(e1,x2) & Actor(e1,x1) & v_look(e1))