There are two workers, one on a ladder, against a blue wall with a yellow-and-black stripe.
Ladders are invaluable tools.
Out of two workers, one is on a ladder, which implies the ladder is an invaluable tool.
exists p1 s1 s2 x1 x2 x3.(against(p1,x2) & with(x2,x3) & n_stripe(x3) & a_yellow-and-black(s2) & Theme(s2,x3) & n_wall(x2) & a_blue(s1) & Theme(s1,x2) & exists x4 x5 x6.((x1 = x4) & rel(x4,x5) & on(x5,x6) & n_ladder(x6) & n_thing(x5) & card_eq_1(x5) & n_worker(x4) & card_eq_2(x4)))
exists p1 x1.(exists s1 x2.((x1 = x2) & n_tool(x2) & a_invaluable(s1) & Theme(s1,x2)) & n_ladder(x1))