A few lemmas about inclusion.

diff --git a/helm/software/matita/library/list/in.ma b/helm/software/matita/library/list/in.ma
index d6c165022aa1e55fc3458fe221c61597c99fa157..310c3f369513d8eac9e8866219d1ae08670c117a 100644 (file)
--- a/helm/software/matita/library/list/in.ma
+++ b/helm/software/matita/library/list/in.ma
@@ -152,4 +152,16 @@ qed.
 
 lemma incl_A_A: ∀T,A.incl T A A.
 intros.unfold incl.intros.assumption.
+qed.
+
+lemma incl_append_l : ∀T,A,B.incl T A (A @ B).
+unfold incl; intros;autobatch.
+qed.
+
+lemma incl_append_r : ∀T,A,B.incl T B (A @ B).
+unfold incl; intros;autobatch.
+qed.
+
+lemma incl_cons : ∀T,A,B,x.incl T A B → incl T (x::A) (x::B).
+unfold incl; intros;elim (in_list_cons_case ? ? ? ? H1);autobatch.
 qed.
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