A boy is walking on a floor covered in graffiti.
The boy is observing the artwork on the floor.
There are many different types if artwork than graffiti.
exists e2 e1 x1 x2 x3 x4.(on(e1,x2) & in(e2,x4) & n_graffitus(x4) & Theme(e2,x3) & v_cover(e2) & (x2 = x3) & n_floor(x2) & Actor(e1,x1) & v_walk(e1) & n_boy(x1))
exists e1 x1 x2 x3.(n_floor(x3) & n_artwork(x2) & n_boy(x1) & on(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_observe(e1))