A man on top of a brown roof.
The man is a roofer.
Just because a man is on top of a roof does not imply he is a roofer.
exists s1 x1 x2 x3.(a_topic(x1) & on(x1,x2) & of(x2,x3) & n_roof(x3) & a_brown(s1) & Theme(s1,x3) & n_top(x2) & n_man(x1))
exists p1 x1.(n_man(x1) & exists x2.((x1 = x2) & n_roofer(x2)))