Corollary consistent_insert_rem : forall {A} (h1 h2 : hist A) a b p v (Hadds : forallb is_add h1 = true),
  consistent (h1 ++ h2) a b -> consistent (h1 ++ QRem p v :: h2) ((p, v) :: a) b.

Lemma interleave_In : forall {A} ls (l' : list A) x (Hinter : interleave ls l'), In x l' <-> exists l, In l ls /\ In x l.