Corollary wf_table_upd_same : forall T k v i (Hwf : wf_table T) (HT : Zlength T = size)
  (Hi : fst (Znth i T) = k) (Hk : k <> 0), wf_table (upd_Znth i T (k, v)).

Lemma sepcon_hoist_if : forall {A} {A_eq : EqDec A} (b c : A) P1 P2 Q, (if eq_dec b c then P1 * Q else P2 * Q) = Q * if eq_dec b c then P1 else P2.