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| -rw-r--r-- | src/Util/ListUtil.v | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/Util/ListUtil.v b/src/Util/ListUtil.v index dded8f224..8260058f1 100644 --- a/src/Util/ListUtil.v +++ b/src/Util/ListUtil.v @@ -986,6 +986,12 @@ Qed. Hint Rewrite @sum_firstn_succ using congruence : simpl_sum_firstn. +Lemma sum_firstn_succ_default_rev : forall l i, + sum_firstn l i = (sum_firstn l (S i) - nth_default 0 l i)%Z. +Proof. + intros; rewrite sum_firstn_succ_default; omega. +Qed. + Lemma sum_firstn_succ_rev : forall l i x, nth_error l i = Some x -> sum_firstn l i = (sum_firstn l (S i) - x)%Z. |