Definition inj_on_list {A B} (l : list A) (f : A -> B) :=
forall x y, In x l -> In y l -> f x = f y -> x = y.
Definition subset_rel {X} (sub lst : list X) : Prop :=
forall x,
In x sub ->
In x lst.
(*** NoDup general lemmas ***)

Lemma up_oram_tr_tree_or_delta o : forall id lvl dlt p,
In id (List.map block_blockid (get_all_blks_tree
(up_oram_tr o lvl dlt p))) ->
In id (List.map block_blockid (get_all_blks_tree o)) \/
In id (List.map block_blockid dlt).