proposition: Lemma split2_append_word : forall sz1 sz2 w1 w2, (split2 sz1 sz2 (append_word w1 w2)) = w2.
proof: Proof. induction w1; simpl; try reflexivity. - intros. unfold append_word; fold @append_word. unfold split2; fold split2. simpl; rewrite IHw1; reflexivity. Qed.
imports: Fiat.Common.Coq__8_4__8_5__Compat Bedrock.Word Coq.ZArith.ZArith Coq.NArith.NArith Coq.Arith.Arith Coq.Numbers.Natural.Peano.NPeano Coq.Logic.Eqdep_dec Fiat.Narcissus.Common.Specs