(** Ordering *)
Inductive vge: aval -> aval -> Prop :=
| vge_bot: forall v, vge v Vbot
| vge_i: forall i, vge (I i) (I i)
| vge_l: forall i, vge (L i) (L i)
| vge_f: forall f, vge (F f) (F f)
| vge_s: forall f, vge (FS f) (FS f)
| vge_uns_i: forall p n i, 0 <= n -> is_uns n i -> vge (Uns p n) (I i)
| vge_uns_uns: forall p1 n1 p2 n2, n1 >= n2 -> pge p1 p2 -> vge (Uns p1 n1) (Uns p2 n2)
| vge_sgn_i: forall p n i, 0 < n -> is_sgn n i -> vge (Sgn p n) (I i)
| vge_sgn_sgn: forall p1 n1 p2 n2, n1 >= n2 -> pge p1 p2 -> vge (Sgn p1 n1) (Sgn p2 n2)
| vge_sgn_uns: forall p1 n1 p2 n2, n1 > n2 -> pge p1 p2 -> vge (Sgn p1 n1) (Uns p2 n2)
| vge_p_p: forall p q, pge p q -> vge (Ptr p) (Ptr q)
| vge_ip_p: forall p q, pge p q -> vge (Ifptr p) (Ptr q)
| vge_ip_ip: forall p q, pge p q -> vge (Ifptr p) (Ifptr q)
| vge_ip_i: forall p i, vge (Ifptr p) (I i)
| vge_ip_l: forall p i, vge (Ifptr p) (L i)
| vge_ip_f: forall p f, vge (Ifptr p) (F f)
| vge_ip_s: forall p f, vge (Ifptr p) (FS f)
| vge_ip_uns: forall p q n, pge p q -> vge (Ifptr p) (Uns q n)
| vge_ip_sgn: forall p q n, pge p q -> vge (Ifptr p) (Sgn q n).
Hint Constructors vge : va.

Lemma vge_trans: forall u v, vge u v -> forall w, vge v w -> vge u w.