Proof using.
elim => [|n ns IH] n' failed; first by rewrite remove_all_nil.
set mfailed := map _ failed.
have H_cn := remove_all_cons name_eq_dec mfailed n ns.
break_or_hyp; break_and; find_rewrite.
move => H_in.
apply IH in H_in.
move: H_in => [H_nin H_in].
split => //.
by right.
rewrite /=.
move => H_in.
case: H_in => H_in.
rewrite H_in.
subst.
split => //.
by left.
apply IH in H_in.
move: H_in => [H_nin H_in].
split => //.
by right.
Qed.

Lemma not_in_map_not_in_failed :
forall failed n,
~ In n (map tot_map_name failed) ->
~ In (tot_map_name_inv n) failed.