(* Why isn't this automatic? *)
Instance zero_ord_preorder : RelationClasses.PreOrder zero_ord.Instance table_incl_preorder : RelationClasses.PreOrder table_incl.

Lemma only_one_add_succeeds : forall k v1 v2 l i1 i2 H0 H (HH : apply_hist H0 l H) (Hin1 : Znth i1 l (HGet 0 0) = HAdd k v1 true) (Hin2 : Znth i2 l (HGet 0 0) = HAdd k v2 true), i2 = i1 /\ v2 = v1.