A young man wearing a backpack and dark glasses approaches the brick building where there is a bit of graffiti on the wall.
There is nothing on the wall but bricks.
Referring to a man, with a backpack and dark glasses, no man in the other sentence. States there's a brick building with some graffito, the other refers to a brick wall with nothing on it.
exists e2 e1 p1 s1 s2 x1 x2 x3 x4 x5 x6 x7 x8.(n_wall(x8) & n_building(x6) & of(x6,x7) & n_brick(x7) & on(e2,x8) & Theme(e2,x6) & Actor(e2,x1) & v_approach(e2) & exists p2 x9 x10 x11.((x9 = x10) & of(x10,x11) & n_graffitus(x11) & n_bit(x10)) & where(x6,p1) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & subset_of(x5,x3) & n_glass(x5) & a_dark(s2) & Theme(s2,x5) & subset_of(x4,x3) & n_backpack(x4) & (x1 = x2) & n_man(x1) & a_young(s1) & Theme(s1,x1))
exists p1 x1 x5.(n_wall(x5) & exists x2 x3.((x1 = x2) & subset_of(x3,x2) & n_brick(x3) & -exists x4.(subset_of(x4,x2) & on(x4,x5) & n_thing(x4))))