Theorem orb_L1_eqs: forall(m:fmap)(x y z:dart), let m1:= L m one x y in let y0:= cA m zero y in inv_hmap m1 -> exd m z -> ~expf m x y0 -> ~expf m x z -> ~expf m y0 z -> eqs (MF.Iter_orb m1 z) (MF.Iter_orb m z).