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-rw-r--r--theories/Lists/Streams.v9
1 files changed, 9 insertions, 0 deletions
diff --git a/theories/Lists/Streams.v b/theories/Lists/Streams.v
index 909c6b49f9..472265f3e3 100644
--- a/theories/Lists/Streams.v
+++ b/theories/Lists/Streams.v
@@ -146,6 +146,15 @@ Inductive Exists ( x: Stream ) : Prop :=
CoInductive ForAll (x: Stream) : Prop :=
HereAndFurther : P x -> ForAll (tl x) -> ForAll x.
+Lemma ForAll_Str_nth_tl : forall m x, ForAll x -> ForAll (Str_nth_tl m x).
+Proof.
+induction m.
+ tauto.
+intros x [_ H].
+simpl.
+apply IHm.
+assumption.
+Qed.
Section Co_Induction_ForAll.
Variable Inv : Stream -> Prop.