X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground%2Flib%2Fstream_eq.ma;h=1e13207763f9d5a6cbf892da04afbb07cf4bd5ea;hb=55c768d7e45babb300b5010463ba3196a68f1bbe;hp=311930686057e113b7d20faecfa5cdb1513220e0;hpb=15212e44902f25536f6e2de4bec4cedcd9a9804d;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/ground/lib/stream_eq.ma b/matita/matita/contribs/lambdadelta/ground/lib/stream_eq.ma
index 311930686..1e1320776 100644
--- a/matita/matita/contribs/lambdadelta/ground/lib/stream_eq.ma
+++ b/matita/matita/contribs/lambdadelta/ground/lib/stream_eq.ma
@@ -18,7 +18,8 @@ include "ground/lib/stream.ma".
 (* EXTENSIONAL EQUIVALENCE FOR STREAMS **************************************)
 
 coinductive stream_eq (A): relation (stream A) ≝
-| stream_eq_cons: ∀t1,t2,b1,b2. b1 = b2 → stream_eq A t1 t2 → stream_eq A (b1⨮t1) (b2⨮t2)
+| stream_eq_cons (a1) (a2) (t1) (t2):
+  a1 = a2 → stream_eq A t1 t2 → stream_eq A (a1⨮t1) (a2⨮t2)
 .
 
 interpretation
@@ -34,39 +35,30 @@ definition stream_eq_repl_back (A) (R:predicate …) ≝
 definition stream_eq_repl_fwd (A) (R:predicate …) ≝
            ∀t1. R t1 → ∀t2. t2 ≗{A} t1 → R t2.
 
-(* Basic inversions *********************************************************)
-
-lemma stream_eq_inv_cons: ∀A,t1,t2. t1 ≗{A} t2 →
-                          ∀u1,u2,a1,a2. a1⨮u1 = t1 → a2⨮u2 = t2 →
-                          u1 ≗ u2 ∧ a1 = a2.
-#A #t1 #t2 * -t1 -t2
-#t1 #t2 #b1 #b2 #Hb #Ht #u1 #u2 #a1 #a2 #H1 #H2 destruct /2 width=1 by conj/
-qed-.
-
 (* Basic constructions ******************************************************)
 
-corec lemma stream_eq_refl: ∀A. reflexive … (stream_eq A).
-#A * #b #t @stream_eq_cons //
+corec lemma stream_eq_refl (A:?):
+            reflexive … (stream_eq A).
+* #a #t @stream_eq_cons //
 qed.
 
-corec lemma stream_eq_sym: ∀A. symmetric … (stream_eq A).
-#A #t1 #t2 * -t1 -t2
-#t1 #t2 #b1 #b2 #Hb #Ht @stream_eq_cons /2 width=1 by/
+corec lemma stream_eq_sym (A):
+            symmetric … (stream_eq A).
+#t1 #t2 * -t1 -t2
+#a1 #a2 #t1 #t2 #Ha #Ht
+@stream_eq_cons /2 width=1 by/
 qed-.
 
-lemma stream_eq_repl_sym: ∀A,R. stream_eq_repl_back A R → stream_eq_repl_fwd A R.
+lemma stream_eq_repl_sym (A) (R):
+      stream_eq_repl_back A R → stream_eq_repl_fwd A R.
 /3 width=3 by stream_eq_sym/ qed-.
 
-(* Main constructions *******************************************************)
+(* Basic inversions *********************************************************)
 
-corec theorem stream_eq_trans: ∀A. Transitive … (stream_eq A).
-#A #t1 #t * -t1 -t
-#t1 #t #b1 #b * #Ht1 * #b2 #t2 #H cases (stream_eq_inv_cons A … H) -H -b
-/3 width=7 by stream_eq_cons/
+lemma stream_eq_inv_cons_bi (A):
+      ∀t1,t2. t1 ≗{A} t2 →
+      ∀u1,u2,b1,b2. b1⨮u1 = t1 → b2⨮u2 = t2 →
+      ∧∧ b1 = b2 & u1 ≗ u2.
+#A #t1 #t2 * -t1 -t2
+#a1 #a2 #t1 #t2 #Ha #Ht #u1 #u2 #b1 #b2 #H1 #H2 destruct /2 width=1 by conj/
 qed-.
-
-theorem stream_eq_canc_sn: ∀A,t,t1,t2. t ≗ t1 → t ≗ t2 → t1 ≗{A} t2.
-/3 width=3 by stream_eq_trans, stream_eq_sym/ qed-.
-
-theorem stream_eq_canc_dx: ∀A,t,t1,t2. t1 ≗ t → t2 ≗ t → t1 ≗{A} t2.
-/3 width=3 by stream_eq_trans, stream_eq_sym/ qed-.