From: matitaweb <claudio.sacerdoticoen@unibo.it>
Date: Wed, 29 Feb 2012 10:45:22 +0000 (+0000)
Subject: commit by user andrea
X-Git-Tag: make_still_working~1928
X-Git-Url: http://matita.cs.unibo.it/gitweb/?p=helm.git;a=commitdiff_plain;h=a5c551d0b7399f00e8eef3dfb06e2a0895eac3d4

commit by user andrea
---

diff --git a/weblib/arithmetics/nat.ma b/weblib/arithmetics/nat.ma
index 66ed6ccfd..24cfc5ef6 100644
--- a/weblib/arithmetics/nat.ma
+++ b/weblib/arithmetics/nat.ma
@@ -47,7 +47,7 @@ theorem not_eq_n_Sn: ∀n:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"n
 theorem nat_case:
  ∀n:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.∀P:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a → Prop. 
   (na title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/aa href="cic:/matita/arithmetics/nat/nat.con(0,1,0)"O/a → P a href="cic:/matita/arithmetics/nat/nat.con(0,1,0)"O/a) → (∀m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. na title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a m → P (a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a m)) → P n.
-#n #P (elim n) /span class="autotactic"2span class="autotrace" trace {}/span/span/ qed.
+#n #P (elim n) /span class="autotactic"2span class="autotrace" trace /span/span/ qed.
 
 theorem nat_elim2 :
  ∀R:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a → a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a → Prop.
@@ -55,7 +55,7 @@ theorem nat_elim2 :
   → (∀n:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. R (a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a n) a href="cic:/matita/arithmetics/nat/nat.con(0,1,0)"O/a)
   → (∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. R n m → R (a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a n) (a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a m))
   → ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. R n m.
-#R #ROn #RSO #RSS #n (elim n) // #n0 #Rn0m #m (cases m) /span class="autotactic"2span class="autotrace" trace {}/span/span/ qed.
+#R #ROn #RSO #RSS #n (elim n) // #n0 #Rn0m #m (cases m) /span class="autotactic"2span class="autotrace" trace /span/span/ qed.
 
 theorem decidable_eq_nat : ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.a href="cic:/matita/basics/logic/decidable.def(1)"decidable/a (na title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/am).
 @a href="cic:/matita/arithmetics/nat/nat_elim2.def(2)"nat_elim2/a #n [ (cases n) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/Or.con(0,1,2)"or_introl/a, a href="cic:/matita/basics/logic/Or.con(0,2,2)"or_intror/a/span/span/ | /span class="autotactic"3span class="autotrace" trace a href="cic:/matita/basics/logic/Or.con(0,2,2)"or_intror/a, a href="cic:/matita/basics/logic/sym_not_eq.def(4)"sym_not_eq/a/span/span/ | #m #Hind (cases Hind) /span class="autotactic"3span class="autotrace" trace a href="cic:/matita/basics/logic/Or.con(0,1,2)"or_introl/a, a href="cic:/matita/basics/logic/Or.con(0,2,2)"or_intror/a, a href="cic:/matita/arithmetics/nat/not_eq_S.def(4)"not_eq_S/a/span/span/]
@@ -500,7 +500,7 @@ qed.
 theorem monotonic_le_plus_r: 
 ∀n:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.a href="cic:/matita/basics/relations/monotonic.def(1)"monotonic/a a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a a href="cic:/matita/arithmetics/nat/le.ind(1,0,1)"le/a (λm.n a title="natural plus" href="cic:/fakeuri.def(1)"+/a m).
 #n #a #b (elim n) normalize //
-#m #H #leab @a href="cic:/matita/arithmetics/nat/le_S_S.def(2)"le_S_S/a /span class="autotactic"2span class="autotrace" trace {}/span/span/ qed.
+#m #H #leab @a href="cic:/matita/arithmetics/nat/le_S_S.def(2)"le_S_S/a /span class="autotactic"2span class="autotrace" trace /span/span/ qed.
 
 (*
 theorem le_plus_r: ∀p,n,m:nat. n ≤ m → p + n ≤ p + m
@@ -529,7 +529,7 @@ lemma le_plus_b: ∀b,n,m. n a title="natural plus" href="cic:/fakeuri.def(1)"
 /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a/span/span/ qed.
 
 theorem le_plus_n_r :∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a m a title="natural plus" href="cic:/fakeuri.def(1)"+/a n.
-/span class="autotactic"2span class="autotrace" trace {}/span/span/ qed.
+/span class="autotactic"2span class="autotrace" trace /span/span/ qed.
 
 theorem eq_plus_to_le: ∀n,m,p:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.na title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/ama title="natural plus" href="cic:/fakeuri.def(1)"+/ap → m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a n.
 // qed.
@@ -560,7 +560,7 @@ monotonic_lt_plus_l. *)
 
 theorem lt_plus: ∀n,m,p,q:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. n a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a m → p a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a q → n a title="natural plus" href="cic:/fakeuri.def(1)"+/a p a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a m a title="natural plus" href="cic:/fakeuri.def(1)"+/a q.
 #n #m #p #q #ltnm #ltpq
-@(a href="cic:/matita/arithmetics/nat/transitive_lt.def(3)"transitive_lt/a ? (na title="natural plus" href="cic:/fakeuri.def(1)"+/aq))/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_lt_plus_l.def(9)"monotonic_lt_plus_l/a, a href="cic:/matita/arithmetics/nat/monotonic_le_plus_r.def(3)"monotonic_le_plus_r/a/span/span/ qed.
+@(a href="cic:/matita/arithmetics/nat/transitive_lt.def(3)"transitive_lt/a ? (na title="natural plus" href="cic:/fakeuri.def(1)"+/aq))/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_plus_r.def(3)"monotonic_le_plus_r/a, a href="cic:/matita/arithmetics/nat/monotonic_lt_plus_l.def(9)"monotonic_lt_plus_l/a/span/span/ qed.
 
 theorem lt_plus_to_lt_l :∀n,p,q:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. pa title="natural plus" href="cic:/fakeuri.def(1)"+/an a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a qa title="natural plus" href="cic:/fakeuri.def(1)"+/an → pa title="natural 'less than'" href="cic:/fakeuri.def(1)"</aq.
 /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_plus_to_le.def(5)"le_plus_to_le/a/span/span/ qed.
@@ -707,7 +707,7 @@ theorem lt_to_le_to_lt_times:
 qed.
 
 theorem lt_times:∀n,m,p,q:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. na title="natural 'less than'" href="cic:/fakeuri.def(1)"</am → pa title="natural 'less than'" href="cic:/fakeuri.def(1)"</aq → na title="natural times" href="cic:/fakeuri.def(1)"*/ap a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a ma title="natural times" href="cic:/fakeuri.def(1)"*/aq.
-#n #m #p #q #ltnm #ltpq @a href="cic:/matita/arithmetics/nat/lt_to_le_to_lt_times.def(12)"lt_to_le_to_lt_times/aspan style="text-decoration: underline;" /span/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_plus_b.def(8)"le_plus_b/a, a href="cic:/matita/arithmetics/nat/ltn_to_ltO.def(5)"ltn_to_ltO/a/span/span/
+#n #m #p #q #ltnm #ltpq @a href="cic:/matita/arithmetics/nat/lt_to_le_to_lt_times.def(12)"lt_to_le_to_lt_times/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_plus_b.def(8)"le_plus_b/a, a href="cic:/matita/arithmetics/nat/ltn_to_ltO.def(5)"ltn_to_ltO/a/span/span/ 
 qed.
 
 theorem lt_times_n_to_lt_l: 
@@ -824,7 +824,7 @@ theorem plus_minus:
 qed.
 
 theorem minus_plus_m_m: ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.n a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a (na title="natural plus" href="cic:/fakeuri.def(1)"+/am)a title="natural minus" href="cic:/fakeuri.def(1)"-/am.
-/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/plus_minus.def(5)"plus_minus/a, a href="cic:/matita/arithmetics/nat/le.con(0,1,1)"le_n/a/span/span/ qed.
+/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le.con(0,1,1)"le_n/a, a href="cic:/matita/arithmetics/nat/plus_minus.def(5)"plus_minus/a/span/span/ qed.
 
 theorem plus_minus_m_m: ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.
   m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a n → n a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a (na title="natural minus" href="cic:/fakeuri.def(1)"-/am)a title="natural plus" href="cic:/fakeuri.def(1)"+/am.
@@ -915,11 +915,11 @@ theorem le_minus_to_plus: ∀n,m,p. na title="natural minus" href="cic:/fakeuri
 qed.
 
 theorem le_minus_to_plus_r: ∀a,b,c. c a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a b → a a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a b a title="natural minus" href="cic:/fakeuri.def(1)"-/a c → a a title="natural plus" href="cic:/fakeuri.def(1)"+/a c a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a b.
-#a #b #c #Hlecb #H >(a href="cic:/matita/arithmetics/nat/plus_minus_m_m.def(7)"plus_minus_m_m/a … Hlecb) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_plus_l.def(6)"monotonic_le_plus_l/a/span/span/
+#a #b #c #Hlecb #H >(a href="cic:/matita/arithmetics/nat/plus_minus_m_m.def(7)"plus_minus_m_m/a … Hlecb) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_minus_to_plus.def(10)"le_minus_to_plus/a/span/span/
 qed.
 
 theorem le_plus_to_minus: ∀n,m,p. n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a pa title="natural plus" href="cic:/fakeuri.def(1)"+/am → na title="natural minus" href="cic:/fakeuri.def(1)"-/am a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a p.
-#n #m #p #lep /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_minus_l.def(10)"monotonic_le_minus_l/a/span/span/ qed.
+#n #m #p #lep /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_minus_l.def(9)"monotonic_le_minus_l/a/span/span/ qed.
 
 theorem le_plus_to_minus_r: ∀a,b,c. a a title="natural plus" href="cic:/fakeuri.def(1)"+/a b a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a c → a a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a c a title="natural minus" href="cic:/fakeuri.def(1)"-/ab.
 #a #b #c #H @(a href="cic:/matita/arithmetics/nat/le_plus_to_le_r.def(6)"le_plus_to_le_r/a … b) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a/span/span/
@@ -931,12 +931,12 @@ theorem lt_minus_to_plus: ∀a,b,c. a a title="natural minus" href="cic:/fakeur
 qed.
 
 theorem lt_minus_to_plus_r: ∀a,b,c. a a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a b a title="natural minus" href="cic:/fakeuri.def(1)"-/a c → a a title="natural plus" href="cic:/fakeuri.def(1)"+/a c a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a b.
-#a #b #c #H @a href="cic:/matita/arithmetics/nat/not_le_to_lt.def(5)"not_le_to_lt/a @(a href="cic:/matita/basics/logic/not_to_not.def(3)"not_to_not/a … (a href="cic:/matita/arithmetics/nat/le_plus_to_minus.def(11)"le_plus_to_minus/a …))
+#a #b #c #H @a href="cic:/matita/arithmetics/nat/not_le_to_lt.def(5)"not_le_to_lt/a @(a href="cic:/matita/basics/logic/not_to_not.def(3)"not_to_not/a … (a href="cic:/matita/arithmetics/nat/le_plus_to_minus.def(10)"le_plus_to_minus/a …))
 @a href="cic:/matita/arithmetics/nat/lt_to_not_le.def(7)"lt_to_not_le/a //
 qed.
 
 theorem lt_plus_to_minus: ∀n,m,p. m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a n → n a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a pa title="natural plus" href="cic:/fakeuri.def(1)"+/am → na title="natural minus" href="cic:/fakeuri.def(1)"-/am a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a p.
-#n #m #p #lenm #H normalize <a href="cic:/matita/arithmetics/nat/minus_Sn_m.def(5)"minus_Sn_m/a // @a href="cic:/matita/arithmetics/nat/le_plus_to_minus.def(11)"le_plus_to_minus/a //
+#n #m #p #lenm #H normalize <a href="cic:/matita/arithmetics/nat/minus_Sn_m.def(5)"minus_Sn_m/a // @a href="cic:/matita/arithmetics/nat/le_plus_to_minus.def(10)"le_plus_to_minus/a //
 qed.
 
 theorem lt_plus_to_minus_r: ∀a,b,c. a a title="natural plus" href="cic:/fakeuri.def(1)"+/a b a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a c → a a title="natural 'less than'" href="cic:/fakeuri.def(1)"</a c a title="natural minus" href="cic:/fakeuri.def(1)"-/a b.
@@ -945,19 +945,19 @@ qed.
 
 theorem monotonic_le_minus_r: 
 ∀p,q,n:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. q a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a p → na title="natural minus" href="cic:/fakeuri.def(1)"-/ap a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a na title="natural minus" href="cic:/fakeuri.def(1)"-/aq.
-#p #q #n #lepq @a href="cic:/matita/arithmetics/nat/le_plus_to_minus.def(11)"le_plus_to_minus/a
+#p #q #n #lepq @a href="cic:/matita/arithmetics/nat/le_plus_to_minus.def(10)"le_plus_to_minus/a span class="error" title="Parse error: illegal begin of statement"/span
 @(a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a … (a href="cic:/matita/arithmetics/nat/le_plus_minus_m_m.def(9)"le_plus_minus_m_m/a ? q)) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_plus_r.def(3)"monotonic_le_plus_r/a/span/span/
 qed.
 
 theorem eq_minus_O: ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.
   n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a m → na title="natural minus" href="cic:/fakeuri.def(1)"-/am a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/arithmetics/nat/nat.con(0,1,0)"O/a.
-#n #m #lenm @(a href="cic:/matita/arithmetics/nat/le_n_O_elim.def(4)"le_n_O_elim/a (na title="natural minus" href="cic:/fakeuri.def(1)"-/am)) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_minus_r.def(12)"monotonic_le_minus_r/a/span/span/
+#n #m #lenm @(a href="cic:/matita/arithmetics/nat/le_n_O_elim.def(4)"le_n_O_elim/a (na title="natural minus" href="cic:/fakeuri.def(1)"-/am)) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/monotonic_le_minus_r.def(11)"monotonic_le_minus_r/a/span/span/
 qed.
 
 theorem distributive_times_minus: a href="cic:/matita/basics/relations/distributive.def(1)"distributive/a ? a href="cic:/matita/arithmetics/nat/times.fix(0,0,2)"times/a a href="cic:/matita/arithmetics/nat/minus.fix(0,0,1)"minus/a.
 #a #b #c
 (cases (a href="cic:/matita/arithmetics/nat/decidable_lt.def(7)"decidable_lt/a b c)) #Hbc
- [> a href="cic:/matita/arithmetics/nat/eq_minus_O.def(13)"eq_minus_O/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_plus_b.def(8)"le_plus_b/a/span/span/ >a href="cic:/matita/arithmetics/nat/eq_minus_O.def(13)"eq_minus_O/a // 
+ [> a href="cic:/matita/arithmetics/nat/eq_minus_O.def(12)"eq_minus_O/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_plus_b.def(8)"le_plus_b/a/span/span/ >a href="cic:/matita/arithmetics/nat/eq_minus_O.def(12)"eq_minus_O/a // 
   @a href="cic:/matita/arithmetics/nat/monotonic_le_times_r.def(8)"monotonic_le_times_r/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_plus_b.def(8)"le_plus_b/a/span/span/
  |@a href="cic:/matita/basics/logic/sym_eq.def(2)"sym_eq/a (applyS a href="cic:/matita/arithmetics/nat/plus_to_minus.def(7)"plus_to_minus/a) <a href="cic:/matita/arithmetics/nat/distributive_times_plus.def(7)"distributive_times_plus/a 
   @a href="cic:/matita/basics/logic/eq_f.def(3)"eq_f/a (applyS a href="cic:/matita/arithmetics/nat/plus_minus_m_m.def(7)"plus_minus_m_m/a) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/not_lt_to_le.def(6)"not_lt_to_le/a/span/span/
@@ -969,7 +969,7 @@ cases (a href="cic:/matita/arithmetics/nat/decidable_le.def(6)"decidable_le/a
   [@a href="cic:/matita/arithmetics/nat/plus_to_minus.def(7)"plus_to_minus/a @a href="cic:/matita/arithmetics/nat/plus_to_minus.def(7)"plus_to_minus/a <a href="cic:/matita/arithmetics/nat/associative_plus.def(4)"associative_plus/a
    @a href="cic:/matita/arithmetics/nat/minus_to_plus.def(8)"minus_to_plus/a //
   |cut (n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a ma title="natural plus" href="cic:/fakeuri.def(1)"+/ap) [@(a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a … (a href="cic:/matita/arithmetics/nat/le_n_Sn.def(1)"le_n_Sn/a …)) @a href="cic:/matita/arithmetics/nat/not_le_to_lt.def(5)"not_le_to_lt/a //]
-   #H >a href="cic:/matita/arithmetics/nat/eq_minus_O.def(13)"eq_minus_O/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/eq_minus_O.def(13)"eq_minus_O/a, a href="cic:/matita/arithmetics/nat/monotonic_le_minus_l.def(10)"monotonic_le_minus_l/a/span/span/
+   #H >a href="cic:/matita/arithmetics/nat/eq_minus_O.def(12)"eq_minus_O/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/eq_minus_O.def(12)"eq_minus_O/a, a href="cic:/matita/arithmetics/nat/monotonic_le_minus_l.def(9)"monotonic_le_minus_l/a/span/span/ 
   ]
 qed.
 
@@ -998,27 +998,27 @@ match n with
 theorem eqb_elim : ∀ n,m:nat.∀ P:bool → Prop.
 (n=m → (P true)) → (n ≠ m → (P false)) → (P (eqb n m)). 
 @nat_elim2 
-  [#n (cases n) normalize /3/ 
-  |normalize /3/
-  |normalize /4/ 
+  [#n (cases n) normalize /span class="autotactic"3span class="autotrace" trace /span/span/ 
+  |normalize /span class="autotactic"3span class="autotrace" trace a href="cic:/matita/basics/logic/sym_not_eq.def(4)"sym_not_eq/a/span/span/
+  |normalize /span class="autotactic"4span class="autotrace" trace a href="cic:/matita/arithmetics/nat/not_eq_S.def(4)"not_eq_S/a/span/span/ 
   ] 
 qed.
 
 theorem eqb_n_n: ∀n. eqb n n = true.
 #n (elim n) normalize // qed. 
 
-theorem eqb_true_to_eq: ∀n,m:nat. eqb n m = true → n = m.
-#n #m @(eqb_elim n m) // #_ #abs @False_ind /2/ qed.
+theorem eqb_true_to_eq: ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. a href="cic:/matita/arithmetics/nat/eqb.fix(0,0,1)"eqb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → n a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a m.
+#n #m @(a href="cic:/matita/arithmetics/nat/eqb_elim.def(5)"eqb_elim/a n m) // #_ #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ qed.
 
-theorem eqb_false_to_not_eq: ∀n,m:nat. eqb n m = false → n ≠ m.
-#n #m @(eqb_elim n m) /2/ qed.
+theorem eqb_false_to_not_eq: ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a. a href="cic:/matita/arithmetics/nat/eqb.fix(0,0,1)"eqb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a → n a title="leibnitz's non-equality" href="cic:/fakeuri.def(1)"≠/a m.
+#n #m @(a href="cic:/matita/arithmetics/nat/eqb_elim.def(5)"eqb_elim/a n m) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/not_to_not.def(3)"not_to_not/a/span/span/ qed.
 
 theorem eq_to_eqb_true: ∀n,m:nat.n = m → eqb n m = true.
 // qed.
 
-theorem not_eq_to_eqb_false: ∀n,m:nat.
-  n ≠  m → eqb n m = false.
-#n #m #noteq @eqb_elim// #Heq @False_ind /2/ qed.
+theorem not_eq_to_eqb_false: ∀n,m:a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a.
+  n a title="leibnitz's non-equality" href="cic:/fakeuri.def(1)"≠/a  m → a href="cic:/matita/arithmetics/nat/eqb.fix(0,0,1)"eqb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a.
+#n #m #noteq @a href="cic:/matita/arithmetics/nat/eqb_elim.def(5)"eqb_elim/a// #Heq @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ qed.
 
 let rec leb n m ≝ 
 match n with 
@@ -1031,28 +1031,28 @@ match n with
 theorem leb_elim: ∀n,m:nat. ∀P:bool → Prop. 
 (n ≤ m → P true) → (n ≰ m → P false) → P (leb n m).
 @nat_elim2 normalize
-  [/2/
-  |/3/
+  [/span class="autotactic"2span class="autotrace" trace /span/span/
+  |/span class="autotactic"3span class="autotrace" trace /span/span/
   |#n #m #Hind #P #Pt #Pf @Hind
-    [#lenm @Pt @le_S_S // |#nlenm @Pf /2/ ]
+    [#lenm @Pt @a href="cic:/matita/arithmetics/nat/le_S_S.def(2)"le_S_S/a // |#nlenm @Pf /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/not_le_to_not_le_S_S.def(5)"not_le_to_not_le_S_S/a/span/span/ ]
   ]
 qed.
 
-theorem leb_true_to_le:∀n,m.leb n m = true → n ≤ m.
-#n #m @leb_elim // #_ #abs @False_ind /2/ qed.
+theorem leb_true_to_le:∀n,m.a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a m.
+#n #m @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a // #_ #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ qed.
 
 theorem leb_false_to_not_le:∀n,m.
-  leb n m = false → n ≰ m.
-#n #m @leb_elim // #_ #abs @False_ind /2/ qed.
+  a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a → n a title="natural 'neither less nor equal to'" href="cic:/fakeuri.def(1)"≰/a m.
+#n #m @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a // #_ #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ qed.
 
-theorem le_to_leb_true: ∀n,m. n ≤ m → leb n m = true.
-#n #m @leb_elim // #H #H1 @False_ind /2/ qed.
+theorem le_to_leb_true: ∀n,m. n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a m → a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
+#n #m @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a // #H #H1 @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ qed.
 
-theorem not_le_to_leb_false: ∀n,m. n ≰ m → leb n m = false.
-#n #m @leb_elim // #H #H1 @False_ind /2/ qed.
+theorem not_le_to_leb_false: ∀n,m. n a title="natural 'neither less nor equal to'" href="cic:/fakeuri.def(1)"≰/a m → a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a.
+#n #m @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a // #H #H1 @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ qed.
 
 theorem lt_to_leb_false: ∀n,m. m < n → leb n m = false.
-/3/ qed.
+/span class="autotactic"3span class="autotrace" trace a href="cic:/matita/arithmetics/nat/lt_to_not_le.def(7)"lt_to_not_le/a, a href="cic:/matita/arithmetics/nat/not_le_to_leb_false.def(7)"not_le_to_leb_false/a/span/span/ qed.
 
 (* serve anche ltb? 
 ndefinition ltb ≝λn,m. leb (S n) m.
@@ -1080,40 +1080,40 @@ theorem le_to_ltb_false: ∀n,m. m \le n → ltb n m = false.
 qed. *)
 
 (* min e max *)
-definition min: nat →nat →nat ≝
-λn.λm. if_then_else ? (leb n m) n m.
+definition min: a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a →a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a →a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a ≝
+λn.λm. if (a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m) then n else m.
 
-definition max: nat →nat →nat ≝
-λn.λm. if_then_else ? (leb n m) m n.
+definition max: a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a →a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a →a href="cic:/matita/arithmetics/nat/nat.ind(1,0,0)"nat/a ≝
+λn.λm. if (a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m) then m else n.
 
-lemma commutative_min: commutative ? min.
-#n #m normalize @leb_elim 
-  [@leb_elim normalize /2/
-  |#notle >(le_to_leb_true …) // @(transitive_le ? (S m)) /2/
+lemma commutative_min: a href="cic:/matita/basics/relations/commutative.def(1)"commutative/a ? a href="cic:/matita/arithmetics/nat/min.def(2)"min/a.
+#n #m normalize @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a 
+  [@a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a normalize /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_to_le_to_eq.def(5)"le_to_le_to_eq/a/span/span/
+  |#notle >(a href="cic:/matita/arithmetics/nat/le_to_leb_true.def(7)"le_to_leb_true/a …) // @(a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a ? (a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a m)) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/not_le_to_lt.def(5)"not_le_to_lt/a/span/span/
   ] qed.
 
-lemma le_minr: ∀i,n,m. i ≤ min n m → i ≤ m.
-#i #n #m normalize @leb_elim normalize /2/ qed. 
+lemma le_minr: ∀i,n,m. i a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a a href="cic:/matita/arithmetics/nat/min.def(2)"min/a n m → i a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a m.
+#i #n #m normalize @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a normalize /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a/span/span/ qed. 
 
 lemma le_minl: ∀i,n,m. i ≤ min n m → i ≤ n.
-/2/ qed.
+/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_minr.def(7)"le_minr/a/span/span/ qed.
 
 lemma to_min: ∀i,n,m. i ≤ n → i ≤ m → i ≤ min n m.
 #i #n #m #lein #leim normalize (cases (leb n m)) 
 normalize // qed.
 
-lemma commutative_max: commutative ? max.
-#n #m normalize @leb_elim 
-  [@leb_elim normalize /2/
-  |#notle >(le_to_leb_true …) // @(transitive_le ? (S m)) /2/
+lemma commutative_max: a href="cic:/matita/basics/relations/commutative.def(1)"commutative/a ? a href="cic:/matita/arithmetics/nat/max.def(2)"max/a.
+#n #m normalize @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a 
+  [@a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a normalize /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_to_le_to_eq.def(5)"le_to_le_to_eq/a/span/span/
+  |#notle >(a href="cic:/matita/arithmetics/nat/le_to_leb_true.def(7)"le_to_leb_true/a …) // @(a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a ? (a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a m)) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/not_le_to_lt.def(5)"not_le_to_lt/a/span/span/
   ] qed.
 
-lemma le_maxl: ∀i,n,m. max n m ≤ i → n ≤ i.
-#i #n #m normalize @leb_elim normalize /2/ qed. 
+lemma le_maxl: ∀i,n,m. a href="cic:/matita/arithmetics/nat/max.def(2)"max/a n m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a i → n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a i.
+#i #n #m normalize @a href="cic:/matita/arithmetics/nat/leb_elim.def(6)"leb_elim/a normalize /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/transitive_le.def(3)"transitive_le/a/span/span/ qed. 
 
 lemma le_maxr: ∀i,n,m. max n m ≤ i → m ≤ i.
-/2/ qed.
+/span class="autotactic"2span class="autotrace" trace a href="cic:/matita/arithmetics/nat/le_maxl.def(7)"le_maxl/a/span/span/ qed.
 
-lemma to_max: ∀i,n,m. n ≤ i → m ≤ i → max n m ≤ i.
-#i #n #m #leni #lemi normalize (cases (leb n m)) 
+lemma to_max: ∀i,n,m. n a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a i → m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a i → a href="cic:/matita/arithmetics/nat/max.def(2)"max/a n m a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a i.
+#i #n #m #leni #lemi normalize (cases (a href="cic:/matita/arithmetics/nat/leb.fix(0,0,1)"leb/a n m)) 
 normalize // qed.
\ No newline at end of file
diff --git a/weblib/basics/list.ma b/weblib/basics/list.ma
index 7d0c2ba13..245a9fd3b 100644
--- a/weblib/basics/list.ma
+++ b/weblib/basics/list.ma
@@ -9,8 +9,7 @@
      \ /   GNU General Public License Version 2   
       V_______________________________________________________________ *)
 
-include "basics/bool.ma".
-(* include "arithmetics/nat.ma". *)
+include "arithmetics/nat.ma".
 
 inductive list (A:Type[0]) : Type[0] :=
   | nil: list A
@@ -31,12 +30,12 @@ notation "hvbox(l1 break @ l2)"
 interpretation "nil" 'nil = (nil ?).
 interpretation "cons" 'cons hd tl = (cons ? hd tl).
 
-definition not_nil: ∀A:Type[0].list A → Prop ≝
- λA.λl.match l with [ nil ⇒ True | cons hd tl ⇒ False ].
+definition not_nil: ∀A:Type[0].a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A → Prop ≝
+ λA.λl.match l with [ nil ⇒ a href="cic:/matita/basics/logic/True.ind(1,0,0)"True/a | cons hd tl ⇒ a href="cic:/matita/basics/logic/False.ind(1,0,0)"False/a ].
 
 theorem nil_cons:
-  ∀A:Type[0].∀l:list A.∀a:A. a::l ≠ [].
-  #A #l #a @nmk #Heq (change with (not_nil ? (a::l))) >Heq //
+  ∀A:Type[0].∀l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.∀a:A. aa title="cons" href="cic:/fakeuri.def(1)":/a:l a title="leibnitz's non-equality" href="cic:/fakeuri.def(1)"≠/a a title="nil" href="cic:/fakeuri.def(1)"[/a].
+  #A #l #a @a href="cic:/matita/basics/logic/Not.con(0,1,1)"nmk/a #Heq (change with (a href="cic:/matita/basics/list/not_nil.def(1)"not_nil/a ? (aa title="cons" href="cic:/fakeuri.def(1)":/a:l))) >Heq //
 qed.
 
 (*
@@ -45,24 +44,24 @@ let rec id_list A (l: list A) on l :=
   [ nil => []
   | (cons hd tl) => hd :: id_list A tl ]. *)
 
-let rec append A (l1: list A) l2 on l1 ≝ 
+let rec append A (l1: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) l2 on l1 ≝ 
   match l1 with
   [ nil ⇒  l2
-  | cons hd tl ⇒  hd :: append A tl l2 ].
+  | cons hd tl ⇒  hd a title="cons" href="cic:/fakeuri.def(1)":/a: append A tl l2 ].
 
-definition hd ≝ λA.λl: list A.λd:A.
+definition hd ≝ λA.λl: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.λd:A.
   match l with [ nil ⇒ d | cons a _ ⇒ a].
 
-definition tail ≝  λA.λl: list A.
-  match l with [ nil ⇒  [] | cons hd tl ⇒  tl].
+definition tail ≝  λA.λl: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.
+  match l with [ nil ⇒  a title="nil" href="cic:/fakeuri.def(1)"[/a] | cons hd tl ⇒  tl].
 
 interpretation "append" 'append l1 l2 = (append ? l1 l2).
 
-theorem append_nil: ∀A.∀l:list A.l @ [] = l.
+theorem append_nil: ∀A.∀l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.l a title="append" href="cic:/fakeuri.def(1)"@/a a title="nil" href="cic:/fakeuri.def(1)"[/a] a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a l.
 #A #l (elim l) normalize // qed.
 
 theorem associative_append: 
- ∀A.associative (list A) (append A).
+ ∀A.a href="cic:/matita/basics/relations/associative.def(1)"associative/a (a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) (a href="cic:/matita/basics/list/append.fix(0,1,1)"append/a A).
 #A #l1 #l2 #l3 (elim l1) normalize // qed.
 
 (* deleterio per auto 
@@ -71,41 +70,51 @@ ntheorem cons_append_commute:
     a :: (l1 @ l2) = (a :: l1) @ l2.
 //; nqed. *)
 
-theorem append_cons:∀A.∀a:A.∀l,l1.l@(a::l1)=(l@[a])@l1.
-/span class="autotactic"2span class="autotrace" trace trans_eq/span/span/ qed.
+theorem append_cons:∀A.∀a:A.∀l,l1.la title="append" href="cic:/fakeuri.def(1)"@/a(aa title="cons" href="cic:/fakeuri.def(1)":/a:l1)a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a(la title="append" href="cic:/fakeuri.def(1)"@/a(aa title="cons" href="cic:/fakeuri.def(1)":/a:a title="nil" href="cic:/fakeuri.def(1)"[/a]))a title="append" href="cic:/fakeuri.def(1)"@/al1.span style="text-decoration: underline;"/spanspan class="autotactic"/span
+#A #a #l1 #l2 >a href="cic:/matita/basics/list/associative_append.def(4)"associative_append/a // qed.
 
-theorem nil_append_elim: ∀A.∀l1,l2: list A.∀P:?→?→Prop. 
-  l1@l2=[] → P (nil A) (nil A) → P l1 l2.
+theorem nil_append_elim: ∀A.∀l1,l2: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.∀P:?→?→Prop. 
+  l1a title="append" href="cic:/fakeuri.def(1)"@/al2a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/aa title="nil" href="cic:/fakeuri.def(1)"[/a] → P (a href="cic:/matita/basics/list/list.con(0,1,1)"nil/a A) (a href="cic:/matita/basics/list/list.con(0,1,1)"nil/a A) → P l1 l2.
 #A #l1 #l2 #P (cases l1) normalize //
 #a #l3 #heq destruct
 qed.
 
-theorem nil_to_nil:  ∀A.∀l1,l2:list A.
-  l1@l2 = [] → l1 = [] ∧ l2 = [].
-#A #l1 #l2 #isnil @(nil_append_elim A l1 l2) /span class="autotactic"2span class="autotrace" trace conj/span/span/
+theorem nil_to_nil:  ∀A.∀l1,l2:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.
+  l1a title="append" href="cic:/fakeuri.def(1)"@/al2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a title="nil" href="cic:/fakeuri.def(1)"[/a] → l1 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a title="nil" href="cic:/fakeuri.def(1)"[/a] a title="logical and" href="cic:/fakeuri.def(1)"∧/a l2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a title="nil" href="cic:/fakeuri.def(1)"[/a].
+#A #l1 #l2 #isnil @(a href="cic:/matita/basics/list/nil_append_elim.def(4)"nil_append_elim/a A l1 l2) /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/And.con(0,1,2)"conj/a/span/span/
 qed.
 
 (* iterators *)
 
-let rec map (A,B:Type[0]) (f: A → B) (l:list A) on l: list B ≝
- match l with [ nil ⇒ nil ? | cons x tl ⇒ f x :: (map A B f tl)].
+let rec map (A,B:Type[0]) (f: A → B) (l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) on l: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a B ≝
+ match l with [ nil ⇒ a href="cic:/matita/basics/list/list.con(0,1,1)"nil/a ? | cons x tl ⇒ f x a title="cons" href="cic:/fakeuri.def(1)":/a: (map A B f tl)].
   
-let rec foldr (A,B:Type[0]) (f:A → B → B) (b:B) (l:list A) on l :B ≝  
+lemma map_append : ∀A,B,f,l1,l2.
+  (a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a A B f l1) a title="append" href="cic:/fakeuri.def(1)"@/a (a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a A B f l2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a A B f (l1a title="append" href="cic:/fakeuri.def(1)"@/al2).
+#A #B #f #l1 elim l1
+[ #l2 @a href="cic:/matita/basics/logic/eq.con(0,1,2)"refl/a
+| #h #t #IH #l2 normalize //
+] qed.
+
+let rec foldr (A,B:Type[0]) (f:A → B → B) (b:B) (l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) on l :B ≝  
  match l with [ nil ⇒ b | cons a l ⇒ f a (foldr A B f b l)].
  
 definition filter ≝ 
-  λT.λp:T → bool.
-  foldr T (list T) (λx,l0.if_then_else ? (p x) (x::l0) l0) (nil T).
+  λT.λp:T → a href="cic:/matita/basics/bool/bool.ind(1,0,0)"bool/a.
+  a href="cic:/matita/basics/list/foldr.fix(0,4,1)"foldr/a T (a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a T) (λx,l0.if (p x) then (xa title="cons" href="cic:/fakeuri.def(1)":/a:l0) else l0) (a href="cic:/matita/basics/list/list.con(0,1,1)"nil/a T).
 
-lemma filter_true : ∀A,l,a,p. p a = true → 
-  filter A p (a::l) = a :: filter A p l.
+definition compose ≝ λA,B,C.λf:A→B→C.λl1,l2.
+    a href="cic:/matita/basics/list/foldr.fix(0,4,1)"foldr/a ?? (λi,acc.(a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a ?? (f i) l2)a title="append" href="cic:/fakeuri.def(1)"@/aacc) a title="nil" href="cic:/fakeuri.def(1)"[/a ] l1.
+
+lemma filter_true : ∀A,l,a,p. p a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → 
+  a href="cic:/matita/basics/list/filter.def(2)"filter/a A p (aa title="cons" href="cic:/fakeuri.def(1)":/a:l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a a title="cons" href="cic:/fakeuri.def(1)":/a: a href="cic:/matita/basics/list/filter.def(2)"filter/a A p l.
 #A #l #a #p #pa (elim l) normalize >pa normalize // qed.
 
-lemma filter_false : ∀A,l,a,p. p a = false → 
-  filter A p (a::l) = filter A p l.
+lemma filter_false : ∀A,l,a,p. p a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a → 
+  a href="cic:/matita/basics/list/filter.def(2)"filter/a A p (aa title="cons" href="cic:/fakeuri.def(1)":/a:l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/list/filter.def(2)"filter/a A p l.
 #A #l #a #p #pa (elim l) normalize >pa normalize // qed.
 
-theorem eq_map : ∀A,B,f,g,l. (∀x.f x = g x) → map A B f l = map A B g l.
+theorem eq_map : ∀A,B,f,g,l. (∀x.f x a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a g x) → a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a A B f l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a A B g l.
 #A #B #f #g #l #eqfg (elim l) normalize // qed.
 
 (*
@@ -115,28 +124,34 @@ match l1 with
   | cons a tl ⇒ (map ??(dp ?? a) (g a)) @ dprodl A f tl g
   ]. *)
 
-(**************************** length ******************************
+(**************************** length *******************************)
 
-let rec length (A:Type[0]) (l:list A) on l ≝ 
+let rec length (A:Type[0]) (l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) on l ≝ 
   match l with 
-    [ nil ⇒ 0
-    | cons a tl ⇒ S (length A tl)].
+    [ nil ⇒ a title="natural number" href="cic:/fakeuri.def(1)"0/a
+    | cons a tl ⇒ a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"S/a (length A tl)].
 
 notation "|M|" non associative with precedence 60 for @{'norm $M}.
 interpretation "norm" 'norm l = (length ? l).
 
-let rec nth n (A:Type[0]) (l:list A) (d:A)  ≝  
+lemma length_append: ∀A.∀l1,l2:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A. 
+  a title="norm" href="cic:/fakeuri.def(1)"|/al1a title="append" href="cic:/fakeuri.def(1)"@/al2| a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a title="norm" href="cic:/fakeuri.def(1)"|/al1|a title="natural plus" href="cic:/fakeuri.def(1)"+/aa title="norm" href="cic:/fakeuri.def(1)"|/al2|.
+#A #l1 elim l1 // normalize /span class="autotactic"2span class="autotrace" trace /span/span/
+qed.
+
+let rec nth n (A:Type[0]) (l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) (d:A)  ≝  
   match n with
-    [O ⇒ hd A l d
-    |S m ⇒ nth m A (tail A l) d].
+    [O ⇒ a href="cic:/matita/basics/list/hd.def(1)"hd/a A l d
+    |S m ⇒ nth m A (a href="cic:/matita/basics/list/tail.def(1)"tail/a A l) d].
 
-**************************** fold *******************************)
+(***************************** fold *******************************)
 
-let rec fold (A,B:Type[0]) (op:B → B → B) (b:B) (p:A→bool) (f:A→B) (l:list A) on l :B ≝  
+let rec fold (A,B:Type[0]) (op:B → B → B) (b:B) (p:A→a href="cic:/matita/basics/bool/bool.ind(1,0,0)"bool/a) (f:A→B) (l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) on l :B ≝  
  match l with 
   [ nil ⇒ b 
-  | cons a l ⇒ if_then_else ? (p a) (op (f a) (fold A B op b p f l))
-      (fold A B op b p f l)].
+  | cons a l ⇒ if (p a) then (op (f a) (fold A B op b p f l))
+      else (fold A B op b p f l)
+  ].
       
 notation "\fold  [ op , nil ]_{ ident i ∈ l | p} f"
   with precedence 80
@@ -149,37 +164,37 @@ for @{'fold $op $nil (λ${ident i}.true) (λ${ident i}. $f) $l}.
 interpretation "\fold" 'fold op nil p f l = (fold ? ? op nil p f l).
 
 theorem fold_true: 
-∀A,B.∀a:A.∀l.∀p.∀op:B→B→B.∀nil.∀f:A→B. p a = true → 
-  \fold[op,nil]_{i ∈ a::l| p i} (f i) = 
-    op (f a) \fold[op,nil]_{i ∈ l| p i} (f i). 
+∀A,B.∀a:A.∀l.∀p.∀op:B→B→B.∀nil.∀f:A→B. p a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → 
+  a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i ∈ aa title="cons" href="cic:/fakeuri.def(1)":/a:l| p i} (f i) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a 
+    op (f a) a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i ∈ l| p i} (f i). 
 #A #B #a #l #p #op #nil #f #pa normalize >pa // qed.
 
 theorem fold_false: 
 ∀A,B.∀a:A.∀l.∀p.∀op:B→B→B.∀nil.∀f.
-p a = false → \fold[op,nil]_{i ∈ a::l| p i} (f i) = 
-  \fold[op,nil]_{i ∈ l| p i} (f i).
+p a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a → a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i ∈ aa title="cons" href="cic:/fakeuri.def(1)":/a:l| p i} (f i) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a 
+  a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i ∈ l| p i} (f i).
 #A #B #a #l #p #op #nil #f #pa normalize >pa // qed.
 
 theorem fold_filter: 
 ∀A,B.∀a:A.∀l.∀p.∀op:B→B→B.∀nil.∀f:A →B.
-  \fold[op,nil]_{i ∈ l| p i} (f i) = 
-    \fold[op,nil]_{i ∈ (filter A p l)} (f i).
+  a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i ∈ l| p i} (f i) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a 
+    a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i ∈ (a href="cic:/matita/basics/list/filter.def(2)"filter/a A p l)} (f i).
 #A #B #a #l #p #op #nil #f elim l //  
-#a #tl #Hind cases(true_or_false (p a)) #pa 
-  [ >filter_true // > fold_true // >fold_true //
-  | >filter_false // >fold_false // ]
+#a #tl #Hind cases(a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (p a)) #pa 
+  [ >a href="cic:/matita/basics/list/filter_true.def(3)"filter_true/a // > a href="cic:/matita/basics/list/fold_true.def(3)"fold_true/a // >a href="cic:/matita/basics/list/fold_true.def(3)"fold_true/a //
+  | >a href="cic:/matita/basics/list/filter_false.def(3)"filter_false/a // >a href="cic:/matita/basics/list/fold_false.def(3)"fold_false/a // ]
 qed.
 
 record Aop (A:Type[0]) (nil:A) : Type[0] ≝
   {op :2> A → A → A; 
-   nill:∀a. op nil a = a; 
-   nilr:∀a. op a nil = a;
-   assoc: ∀a,b,c.op a (op b c) = op (op a b) c
+   nill:∀a. op nil a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a; 
+   nilr:∀a. op a nil a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a;
+   assoc: ∀a,b,c.op a (op b c) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a op (op a b) c
   }.
 
-theorem fold_sum: ∀A,B. ∀I,J:list A.∀nil.∀op:Aop B nil.∀f.
-  op (\fold[op,nil]_{i∈I} (f i)) (\fold[op,nil]_{i∈J} (f i)) =
-    \fold[op,nil]_{i∈(I@J)} (f i).
+theorem fold_sum: ∀A,B. ∀I,J:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A.∀nil.∀op:a href="cic:/matita/basics/list/Aop.ind(1,0,2)"Aop/a B nil.∀f.
+  op (a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i∈I} (f i)) (a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i∈J} (f i)) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a
+    a title="\fold" href="cic:/fakeuri.def(1)"\fold/a[op,nil]_{i∈(Ia title="append" href="cic:/fakeuri.def(1)"@/aJ)} (f i).
 #A #B #I #J #nil #op #f (elim I) normalize 
-  [>nill //|#a #tl #Hind <assoc //]
+  [>a href="cic:/matita/basics/list/nill.fix(0,2,2)"nill/a //|#a #tl #Hind <a href="cic:/matita/basics/list/assoc.fix(0,2,2)"assoc/a //]
 qed.
\ No newline at end of file
diff --git a/weblib/tutorial/chapter5.ma b/weblib/tutorial/chapter5.ma
index 12df4cc6d..d0bf2c5d6 100644
--- a/weblib/tutorial/chapter5.ma
+++ b/weblib/tutorial/chapter5.ma
@@ -1,170 +1,173 @@
-(* boolean functions over lists *)
+(* The fact of being able to decide, via a computable boolean function, the 
+equality between elements of a given set is an essential prerequisite for 
+effectively searching an element of that set inside a data structure. In this 
+section we shall define several boolean functions acting on lists of elements in 
+a DeqSet, and prove some of their properties.*)
 
 include "basics/list.ma".
-include "basics/sets.ma".
-include "basics/deqsets.ma".
+include "tutorial/chapter4.ma".
 
 (********* search *********)
 
-let rec memb (S:DeqSet) (x:S) (l: list S) on l  ≝
+let rec memb (S:a href="cic:/matita/tutorial/chapter4/DeqSet.ind(1,0,0)"DeqSet/a) (x:S) (l: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a S) on l  ≝
   match l with
-  [ nil ⇒ false
-  | cons a tl ⇒ (x == a) ∨ memb S x tl
+  [ nil ⇒ a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a
+  | cons a tl ⇒ (x a title="eqb" href="cic:/fakeuri.def(1)"=/a= a) a title="boolean or" href="cic:/fakeuri.def(1)"∨/a memb S x tl
   ].
 
 notation < "\memb x l" non associative with precedence 90 for @{'memb $x $l}.
 interpretation "boolean membership" 'memb a l = (memb ? a l).
 
-lemma memb_hd: ∀S,a,l. memb S a (a::l) = true.
-#S #a #l normalize >(proj2 … (eqb_true S …) (refl S a)) //
+lemma memb_hd: ∀S,a,l. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (aa title="cons" href="cic:/fakeuri.def(1)":/a:l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
+#S #a #l normalize >(a href="cic:/matita/basics/logic/proj2.def(2)"proj2/a … (a href="cic:/matita/tutorial/chapter4/eqb_true.fix(0,0,4)"eqb_true/a S …) (a href="cic:/matita/basics/logic/eq.con(0,1,2)"refl/a S a)) //
 qed.
 
 lemma memb_cons: ∀S,a,b,l. 
-  memb S a l = true → memb S a (b::l) = true.
-#S #a #b #l normalize cases (a==b) normalize // 
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (ba title="cons" href="cic:/fakeuri.def(1)":/a:l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
+#S #a #b #l normalize cases (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b) normalize // 
 qed.
 
-lemma memb_single: ∀S,a,x. memb S a [x] = true → a = x.
-#S #a #x normalize cases (true_or_false … (a==x)) #H
-  [#_ >(\P H) // |>H normalize #abs @False_ind /2/]
+lemma memb_single: ∀S,a,x. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a a title="cons" href="cic:/fakeuri.def(1)"[/ax] a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a x.
+#S #a #x normalize cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a … (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=x)) #H
+  [#_ >(\P H) // |>H normalize #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/]
 qed.
 
 lemma memb_append: ∀S,a,l1,l2. 
-memb S a (l1@l2) = true →
-  memb S a l1= true ∨ memb S a l2 = true.
+a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (l1a title="append" href="cic:/fakeuri.def(1)"@/al2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a →
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l1a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a a title="logical or" href="cic:/fakeuri.def(1)"∨/a a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S #a #l1 elim l1 normalize [#l2 #H %2 //] 
-#b #tl #Hind #l2 cases (a==b) normalize /2/ 
+#b #tl #Hind #l2 cases (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b) normalize /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/bool/orb_true_l.def(2)"orb_true_l/a/span/span/ 
 qed. 
 
 lemma memb_append_l1: ∀S,a,l1,l2. 
- memb S a l1= true → memb S a (l1@l2) = true.
+ a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l1a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (l1a title="append" href="cic:/fakeuri.def(1)"@/al2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S #a #l1 elim l1 normalize
-  [normalize #le #abs @False_ind /2/
-  |#b #tl #Hind #l2 cases (a==b) normalize /2/ 
+  [normalize #le #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/
+  |#b #tl #Hind #l2 cases (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b) normalize /span class="autotactic"2span class="autotrace" trace /span/span/ 
   ]
 qed. 
 
 lemma memb_append_l2: ∀S,a,l1,l2. 
- memb S a l2= true → memb S a (l1@l2) = true.
+ a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l2a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (l1a title="append" href="cic:/fakeuri.def(1)"@/al2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S #a #l1 elim l1 normalize //
-#b #tl #Hind #l2 cases (a==b) normalize /2/ 
+#b #tl #Hind #l2 cases (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b) normalize /span class="autotactic"2span class="autotrace" trace /span/span/ 
 qed. 
 
-lemma memb_exists: ∀S,a,l.memb S a l = true → 
-  ∃l1,l2.l=l1@(a::l2).
-#S #a #l elim l [normalize #abs @False_ind /2/]
-#b #tl #Hind #H cases (orb_true_l … H)
-  [#eqba @(ex_intro … (nil S)) @(ex_intro … tl) >(\P eqba) //
+lemma memb_exists: ∀S,a,l.a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → 
+  a title="exists" href="cic:/fakeuri.def(1)"∃/al1,l2.la title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/al1a title="append" href="cic:/fakeuri.def(1)"@/a(aa title="cons" href="cic:/fakeuri.def(1)":/a:l2).
+#S #a #l elim l [normalize #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/]
+#b #tl #Hind #H cases (a href="cic:/matita/basics/bool/orb_true_l.def(2)"orb_true_l/a … H)
+  [#eqba @(a href="cic:/matita/basics/logic/ex.con(0,1,2)"ex_intro/a … (a href="cic:/matita/basics/list/list.con(0,1,1)"nil/a S)) @(a href="cic:/matita/basics/logic/ex.con(0,1,2)"ex_intro/a … tl) >(\P eqba) //
   |#mem_tl cases (Hind mem_tl) #l1 * #l2 #eqtl
-   @(ex_intro … (b::l1)) @(ex_intro … l2) >eqtl //
+   @(a href="cic:/matita/basics/logic/ex.con(0,1,2)"ex_intro/a … (ba title="cons" href="cic:/fakeuri.def(1)":/a:l1)) @(a href="cic:/matita/basics/logic/ex.con(0,1,2)"ex_intro/a … l2) >eqtl //
   ]
 qed.
 
 lemma not_memb_to_not_eq: ∀S,a,b,l. 
- memb S a l = false → memb S b l = true → a==b = false.
-#S #a #b #l cases (true_or_false (a==b)) // 
-#eqab >(\P eqab) #H >H #abs @False_ind /2/
+ a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S b l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a.
+#S #a #b #l cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b)) // 
+#eqab >(\P eqab) #H >H #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/
 qed. 
  
-lemma memb_map: ∀S1,S2,f,a,l. memb S1 a l= true → 
-  memb S2 (f a) (map … f l) = true.
+lemma memb_map: ∀S1,S2,f,a,l. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S1 a la title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → 
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S2 (f a) (a href="cic:/matita/basics/list/map.fix(0,3,1)"map/a … f l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S1 #S2 #f #a #l elim l normalize [//]
-#x #tl #memba cases (true_or_false (a==x))
-  [#eqx >eqx >(\P eqx) >(\b (refl … (f x))) normalize //
-  |#eqx >eqx cases (f a==f x) normalize /2/
+#x #tl #memba cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=x))
+  [#eqx >eqx >(\P eqx) >(\b (a href="cic:/matita/basics/logic/eq.con(0,1,2)"refl/a … (f x))) normalize //
+  |#eqx >eqx cases (f aa title="eqb" href="cic:/fakeuri.def(1)"=/a=f x) normalize /span class="autotactic"2span class="autotrace" trace /span/span/
   ]
 qed.
 
 lemma memb_compose: ∀S1,S2,S3,op,a1,a2,l1,l2.   
-  memb S1 a1 l1 = true → memb S2 a2 l2 = true →
-  memb S3 (op a1 a2) (compose S1 S2 S3 op l1 l2) = true.
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S1 a1 l1 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S2 a2 l2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a →
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S3 (op a1 a2) (a href="cic:/matita/basics/list/compose.def(2)"compose/a S1 S2 S3 op l1 l2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S1 #S2 #S3 #op #a1 #a2 #l1 elim l1 [normalize //]
-#x #tl #Hind #l2 #memba1 #memba2 cases (orb_true_l … memba1)
-  [#eqa1 >(\P eqa1) @memb_append_l1 @memb_map // 
-  |#membtl @memb_append_l2 @Hind //
+#x #tl #Hind #l2 #memba1 #memba2 cases (a href="cic:/matita/basics/bool/orb_true_l.def(2)"orb_true_l/a … memba1)
+  [#eqa1 >(\P eqa1) @a href="cic:/matita/tutorial/chapter5/memb_append_l1.def(5)"memb_append_l1/a @a href="cic:/matita/tutorial/chapter5/memb_map.def(5)"memb_map/a // 
+  |#membtl @a href="cic:/matita/tutorial/chapter5/memb_append_l2.def(5)"memb_append_l2/a @Hind //
   ]
 qed.
 
 (**************** unicity test *****************)
 
-let rec uniqueb (S:DeqSet) l on l : bool ≝
+let rec uniqueb (S:a href="cic:/matita/tutorial/chapter4/DeqSet.ind(1,0,0)"DeqSet/a) l on l : a href="cic:/matita/basics/bool/bool.ind(1,0,0)"bool/a ≝
   match l with 
-  [ nil ⇒ true
-  | cons a tl ⇒ notb (memb S a tl) ∧ uniqueb S tl
+  [ nil ⇒ a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a
+  | cons a tl ⇒ a href="cic:/matita/basics/bool/notb.def(1)"notb/a (a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a tl) a title="boolean and" href="cic:/fakeuri.def(1)"∧/a uniqueb S tl
   ].
 
 (* unique_append l1 l2 add l1 in fornt of l2, but preserving unicity *)
 
-let rec unique_append (S:DeqSet) (l1,l2: list S) on l1 ≝
+let rec unique_append (S:a href="cic:/matita/tutorial/chapter4/DeqSet.ind(1,0,0)"DeqSet/a) (l1,l2: a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a S) on l1 ≝
   match l1 with
   [ nil ⇒ l2
   | cons a tl ⇒ 
      let r ≝ unique_append S tl l2 in
-     if memb S a r then r else a::r
+     if a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a r then r else aa title="cons" href="cic:/fakeuri.def(1)":/a:r
   ].
 
-axiom unique_append_elim: ∀S:DeqSet.∀P: S → Prop.∀l1,l2. 
-(∀x. memb S x l1 = true → P x) → (∀x. memb S x l2 = true → P x) →
-∀x. memb S x (unique_append S l1 l2) = true → P x. 
+axiom unique_append_elim: ∀S:a href="cic:/matita/tutorial/chapter4/DeqSet.ind(1,0,0)"DeqSet/a.∀P: S → Prop.∀l1,l2. 
+(∀x. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x l1 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → P x) → (∀x. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x l2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → P x) →
+∀x. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S l1 l2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → P x. 
 
-lemma unique_append_unique: ∀S,l1,l2. uniqueb S l2 = true →
-  uniqueb S (unique_append S l1 l2) = true.
+lemma unique_append_unique: ∀S,l1,l2. a href="cic:/matita/tutorial/chapter5/uniqueb.fix(0,1,5)"uniqueb/a S l2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a →
+  a href="cic:/matita/tutorial/chapter5/uniqueb.fix(0,1,5)"uniqueb/a S (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S l1 l2) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S #l1 elim l1 normalize // #a #tl #Hind #l2 #uniquel2
-cases (true_or_false … (memb S a (unique_append S tl l2))) 
+cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a … (a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S tl l2))) 
 #H >H normalize [@Hind //] >H normalize @Hind //
 qed.
 
 (******************* sublist *******************)
 definition sublist ≝ 
-  λS,l1,l2.∀a. memb S a l1 = true → memb S a l2 = true.
+  λS,l1,l2.∀a. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l1 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l2 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 
 lemma sublist_length: ∀S,l1,l2. 
- uniqueb S l1 = true → sublist S l1 l2 → |l1| ≤ |l2|.
+ a href="cic:/matita/tutorial/chapter5/uniqueb.fix(0,1,5)"uniqueb/a S l1 a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/sublist.def(5)"sublist/a S l1 l2 → a title="norm" href="cic:/fakeuri.def(1)"|/al1| a title="natural 'less or equal to'" href="cic:/fakeuri.def(1)"≤/a a title="norm" href="cic:/fakeuri.def(1)"|/al2|.
 #S #l1 elim l1 // 
 #a #tl #Hind #l2 #unique #sub
-cut (∃l3,l4.l2=l3@(a::l4)) [@memb_exists @sub //]
-* #l3 * #l4 #eql2 >eql2 >length_append normalize 
-applyS le_S_S <length_append @Hind [@(andb_true_r … unique)]
+cut (a title="exists" href="cic:/fakeuri.def(1)"∃/al3,l4.l2a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/al3a title="append" href="cic:/fakeuri.def(1)"@/a(aa title="cons" href="cic:/fakeuri.def(1)":/a:l4)) [@a href="cic:/matita/tutorial/chapter5/memb_exists.def(5)"memb_exists/a @sub //]
+* #l3 * #l4 #eql2 >eql2 >a href="cic:/matita/basics/list/length_append.def(2)"length_append/a normalize 
+applyS a href="cic:/matita/arithmetics/nat/le_S_S.def(2)"le_S_S/a <a href="cic:/matita/basics/list/length_append.def(2)"length_append/a @Hind [@(a href="cic:/matita/basics/bool/andb_true_r.def(4)"andb_true_r/a … unique)]
 >eql2 in sub; #sub #x #membx 
-cases (memb_append … (sub x (orb_true_r2 … membx)))
-  [#membxl3 @memb_append_l1 //
-  |#membxal4 cases (orb_true_l … membxal4)
-    [#eqxa @False_ind lapply (andb_true_l … unique)
-     <(\P eqxa) >membx normalize /2/ |#membxl4 @memb_append_l2 //
+cases (a href="cic:/matita/tutorial/chapter5/memb_append.def(5)"memb_append/a … (sub x (a href="cic:/matita/basics/bool/orb_true_r2.def(3)"orb_true_r2/a … membx)))
+  [#membxl3 @a href="cic:/matita/tutorial/chapter5/memb_append_l1.def(5)"memb_append_l1/a //
+  |#membxal4 cases (a href="cic:/matita/basics/bool/orb_true_l.def(2)"orb_true_l/a … membxal4)
+    [#eqxa @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a lapply (a href="cic:/matita/basics/bool/andb_true_l.def(4)"andb_true_l/a … unique)
+     <(\P eqxa) >membx normalize /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/ |#membxl4 @a href="cic:/matita/tutorial/chapter5/memb_append_l2.def(5)"memb_append_l2/a //
     ]
   ]
 qed.
 
 lemma sublist_unique_append_l1: 
-  ∀S,l1,l2. sublist S l1 (unique_append S l1 l2).
-#S #l1 elim l1 normalize [#l2 #S #abs @False_ind /2/]
+  ∀S,l1,l2. a href="cic:/matita/tutorial/chapter5/sublist.def(5)"sublist/a S l1 (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S l1 l2).
+#S #l1 elim l1 normalize [#l2 #S #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/]
 #x #tl #Hind #l2 #a 
-normalize cases (true_or_false … (a==x)) #eqax >eqax 
-[<(\P eqax) cases (true_or_false (memb S a (unique_append S tl l2)))
-  [#H >H normalize // | #H >H normalize >(\b (refl … a)) //]
-|cases (memb S x (unique_append S tl l2)) normalize 
-  [/2/ |>eqax normalize /2/]
+normalize cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a … (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=x)) #eqax >eqax 
+[<(\P eqax) cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S tl l2)))
+  [#H >H normalize // | #H >H normalize >(\b (a href="cic:/matita/basics/logic/eq.con(0,1,2)"refl/a … a)) //]
+|cases (a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S tl l2)) normalize 
+  [/span class="autotactic"2span class="autotrace" trace /span/span/ |>eqax normalize /span class="autotactic"2span class="autotrace" trace /span/span/]
 ]
 qed.
 
 lemma sublist_unique_append_l2: 
-  ∀S,l1,l2. sublist S l2 (unique_append S l1 l2).
+  ∀S,l1,l2. a href="cic:/matita/tutorial/chapter5/sublist.def(5)"sublist/a S l2 (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S l1 l2).
 #S #l1 elim l1 [normalize //] #x #tl #Hind normalize 
-#l2 #a cases (memb S x (unique_append S tl l2)) normalize
-[@Hind | cases (a==x) normalize // @Hind]
+#l2 #a cases (a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x (a href="cic:/matita/tutorial/chapter5/unique_append.fix(0,1,5)"unique_append/a S tl l2)) normalize
+[@Hind | cases (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=x) normalize // @Hind]
 qed.
 
 lemma decidable_sublist:∀S,l1,l2. 
-  (sublist S l1 l2) ∨ ¬(sublist S l1 l2).
+  (a href="cic:/matita/tutorial/chapter5/sublist.def(5)"sublist/a S l1 l2) a title="logical or" href="cic:/fakeuri.def(1)"∨/a a title="logical not" href="cic:/fakeuri.def(1)"¬/a(a href="cic:/matita/tutorial/chapter5/sublist.def(5)"sublist/a S l1 l2).
 #S #l1 #l2 elim l1 
-  [%1 #a normalize in ⊢ (%→?); #abs @False_ind /2/
+  [%1 #a normalize in ⊢ (%→?); #abs @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/
   |#a #tl * #subtl 
-    [cases (true_or_false (memb S a l2)) #memba
-      [%1 whd #x #membx cases (orb_true_l … membx)
+    [cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l2)) #memba
+      [%1 whd #x #membx cases (a href="cic:/matita/basics/bool/orb_true_l.def(2)"orb_true_l/a … membx)
         [#eqax >(\P eqax) // |@subtl]
-      |%2 @(not_to_not … (eqnot_to_noteq … true memba)) #H1 @H1 @memb_hd
+      |%2 @(a href="cic:/matita/basics/logic/not_to_not.def(3)"not_to_not/a … (a href="cic:/matita/basics/bool/eqnot_to_noteq.def(4)"eqnot_to_noteq/a … a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a memba)) #H1 @H1 @a href="cic:/matita/tutorial/chapter5/memb_hd.def(5)"memb_hd/a
       ]
-    |%2 @(not_to_not … subtl) #H1 #x #H2 @H1 @memb_cons //
+    |%2 @(a href="cic:/matita/basics/logic/not_to_not.def(3)"not_to_not/a … subtl) #H1 #x #H2 @H1 @a href="cic:/matita/tutorial/chapter5/memb_cons.def(5)"memb_cons/a //
     ] 
   ]
 qed.
@@ -172,44 +175,38 @@ qed.
 (********************* filtering *****************)
 
 lemma filter_true: ∀S,f,a,l. 
-  memb S a (filter S f l) = true → f a = true.
-#S #f #a #l elim l [normalize #H @False_ind /2/]
-#b #tl #Hind cases (true_or_false (f b)) #H
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (a href="cic:/matita/basics/list/filter.def(2)"filter/a S f l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → f a a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
+#S #f #a #l elim l [normalize #H @a href="cic:/matita/basics/logic/False_ind.fix(0,1,1)"False_ind/a /span class="autotactic"2span class="autotrace" trace a href="cic:/matita/basics/logic/absurd.def(2)"absurd/a/span/span/]
+#b #tl #Hind cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (f b)) #H
 normalize >H normalize [2:@Hind]
-cases (true_or_false (a==b)) #eqab
+cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b)) #eqab
   [#_ >(\P eqab) // | >eqab normalize @Hind]
 qed. 
   
 lemma memb_filter_memb: ∀S,f,a,l. 
-  memb S a (filter S f l) = true → memb S a l = true.
+  a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a (a href="cic:/matita/basics/list/filter.def(2)"filter/a S f l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S a l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S #f #a #l elim l [normalize //]
 #b #tl #Hind normalize (cases (f b)) normalize 
-cases (a==b) normalize // @Hind
+cases (aa title="eqb" href="cic:/fakeuri.def(1)"=/a=b) normalize // @Hind
 qed.
   
-lemma memb_filter: ∀S,f,l,x. memb S x (filter ? f l) = true → 
-memb S x l = true ∧ (f x = true).
-/3/ qed.
+lemma memb_filter: ∀S,f,l,x. a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x (a href="cic:/matita/basics/list/filter.def(2)"filter/a ? f l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a → 
+a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a a title="logical and" href="cic:/fakeuri.def(1)"∧/a (f x a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a).
+/span class="autotactic"3span class="autotrace" trace a href="cic:/matita/basics/logic/And.con(0,1,2)"conj/a, a href="cic:/matita/tutorial/chapter5/filter_true.def(5)"filter_true/a, a href="cic:/matita/tutorial/chapter5/memb_filter_memb.def(5)"memb_filter_memb/a/span/span/ qed.
 
-lemma memb_filter_l: ∀S,f,x,l. (f x = true) → memb S x l = true →
-memb S x (filter ? f l) = true.
+lemma memb_filter_l: ∀S,f,x,l. (f x a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a) → a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x l a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a →
+a href="cic:/matita/tutorial/chapter5/memb.fix(0,2,4)"memb/a S x (a href="cic:/matita/basics/list/filter.def(2)"filter/a ? f l) a title="leibnitz's equality" href="cic:/fakeuri.def(1)"=/a a href="cic:/matita/basics/bool/bool.con(0,1,0)"true/a.
 #S #f #x #l #fx elim l normalize //
-#b #tl #Hind cases (true_or_false (x==b)) #eqxb
-  [<(\P eqxb) >(\b (refl … x)) >fx normalize >(\b (refl … x)) normalize //
+#b #tl #Hind cases (a href="cic:/matita/basics/bool/true_or_false.def(1)"true_or_false/a (xa title="eqb" href="cic:/fakeuri.def(1)"=/a=b)) #eqxb
+  [<(\P eqxb) >(\b (a href="cic:/matita/basics/logic/eq.con(0,1,2)"refl/a … x)) >fx normalize >(\b (a href="cic:/matita/basics/logic/eq.con(0,1,2)"refl/a … x)) normalize //
   |>eqxb cases (f b) normalize [>eqxb normalize @Hind| @Hind]
   ]
 qed. 
 
 (********************* exists *****************)
 
-let rec exists (A:Type[0]) (p:A → bool) (l:list A) on l : bool ≝
+let rec exists (A:Type[0]) (p:A → a href="cic:/matita/basics/bool/bool.ind(1,0,0)"bool/a) (l:a href="cic:/matita/basics/list/list.ind(1,0,1)"list/a A) on l : a href="cic:/matita/basics/bool/bool.ind(1,0,0)"bool/a ≝
 match l with
-[ nil ⇒ false
-| cons h t ⇒ orb (p h) (exists A p t)
+[ nil ⇒ a href="cic:/matita/basics/bool/bool.con(0,2,0)"false/a
+| cons h t ⇒ a href="cic:/matita/basics/bool/orb.def(1)"orb/a (p h) (exists A p t)
 ].
-
-lemma Exists_exists : ∀A,P,l.
-  Exists A P l →
-  ∃x. P x.
-#A #P #l elim l [ * | #hd #tl #IH * [ #H %{hd} @H | @IH ]
-qed.