Remark in_remove:
  forall (A: Type) (eq: forall (x y: A), {x=y}+{x<>y}) x y l,
  In y (List.remove eq x l) <-> x <> y /\ In y l.

Lemma rhs_eval_to_inj: forall valu ge sp m rh v1 v2, rhs_eval_to valu ge sp m rh v1 -> rhs_eval_to valu ge sp m rh v2 -> v1 = v2.