(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on values *)
  Inductive val_obs (mi : memren) : val -> val -> Prop :=
    obs_int : forall i : int, val_obs mi (Vint i) (Vint i)
  | obs_long : forall i : int64, val_obs mi (Vlong i) (Vlong i)
  | obs_float : forall f : Floats.float,
      val_obs mi (Vfloat f) (Vfloat f)
  | obs_single : forall f : Floats.float32,
      val_obs mi (Vsingle f) (Vsingle f)
  | obs_ptr : forall (b1 b2 : block) (ofs : ptrofs),
      mi b1 = Some b2 ->
      val_obs mi (Vptr b1 ofs) (Vptr b2 ofs)
  | obs_undef : val_obs mi Vundef Vundef.(** Strong injections on memory values*)
  Inductive memval_obs_eq (f : memren) : memval -> memval -> Prop :=
  | memval_obs_byte : forall n : byte,
      memval_obs_eq f (Byte n) (Byte n)
  | memval_obs_frag : forall (v1 v2 : val) (q : quantity) (n : nat)
                        (Hval_obs: val_obs f v1 v2),
      memval_obs_eq f (Fragment v1 q n) (Fragment v2 q n)
  | memval_obs_undef : memval_obs_eq f Undef Undef.(** Strong injections on memory values*)
  Inductive memval_obs_eq (f : memren) : memval -> memval -> Prop :=
  | memval_obs_byte : forall n : byte,
      memval_obs_eq f (Byte n) (Byte n)
  | memval_obs_frag : forall (v1 v2 : val) (q : quantity) (n : nat)
                        (Hval_obs: val_obs f v1 v2),
      memval_obs_eq f (Fragment v1 q n) (Fragment v2 q n)
  | memval_obs_undef : memval_obs_eq f Undef Undef.(** Strong injections on memory values*)
  Inductive memval_obs_eq (f : memren) : memval -> memval -> Prop :=
  | memval_obs_byte : forall n : byte,
      memval_obs_eq f (Byte n) (Byte n)
  | memval_obs_frag : forall (v1 v2 : val) (q : quantity) (n : nat)
                        (Hval_obs: val_obs f v1 v2),
      memval_obs_eq f (Fragment v1 q n) (Fragment v2 q n)
  | memval_obs_undef : memval_obs_eq f Undef Undef.(** Strong injections on memory values*)
  Inductive memval_obs_eq (f : memren) : memval -> memval -> Prop :=
  | memval_obs_byte : forall n : byte,
      memval_obs_eq f (Byte n) (Byte n)
  | memval_obs_frag : forall (v1 v2 : val) (q : quantity) (n : nat)
                        (Hval_obs: val_obs f v1 v2),
      memval_obs_eq f (Fragment v1 q n) (Fragment v2 q n)
  | memval_obs_undef : memval_obs_eq f Undef Undef.

Lemma val_obs_ext: forall f v v' n (Hval_obs: val_obs f v v'), val_obs f (Val.zero_ext n v) (Val.zero_ext n v').