X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Flist%2Flist.ma;h=d5664f4166c783914af3be60f1d60bc25a008a79;hb=97c2d258a5c524eb5c4b85208899d80751a2c82f;hp=1973dadab299683c4d775d2d409cdc764843faf4;hpb=9adc60caf3223c659d8b64228e90c25cc8d76530;p=helm.git

diff --git a/helm/matita/library/list/list.ma b/helm/matita/library/list/list.ma
index 1973dadab..d5664f416 100644
--- a/helm/matita/library/list/list.ma
+++ b/helm/matita/library/list/list.ma
@@ -36,6 +36,8 @@ interpretation "nil" 'nil = (cic:/matita/list/list.ind#xpointer(1/1/1) _).
 interpretation "cons" 'cons hd tl =
   (cic:/matita/list/list.ind#xpointer(1/1/2) _ hd tl).
 
+(* theorem test_notation: [O; S O; S (S O)] = O :: S O :: S (S O) :: []. *)
+
 theorem nil_cons:
   \forall A:Set.\forall l:list A.\forall a:A.
     a::l <> [].
@@ -54,6 +56,11 @@ let rec append A (l1: list A) l2 on l1 :=
   [ nil => l2
   | (cons hd tl) => hd :: append A tl l2 ].
 
+definition tail := \lambda A:Set. \lambda l: list A.
+  match l with
+  [ nil => []
+  | (cons hd tl) => tl].
+
 interpretation "append" 'append l1 l2 = (cic:/matita/list/append.con _ l1 l2).
 
 theorem append_nil: \forall A:Set.\forall l:list A.l @ [] = l.