X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fbasic_2%2Fstatic%2Fsd.ma;h=a16d19042f255cb88a34ec19517afbe257bc0ade;hb=ae22633ad934bba5fb32143f1726cdfbd255b899;hp=0c899ad444fca856e47f68de32d0cfcaea081996;hpb=f62eeb3c7824564ccbe4fff6e75ddee46ca39cc0;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/basic_2/static/sd.ma b/matita/matita/contribs/lambdadelta/basic_2/static/sd.ma
index 0c899ad44..a16d19042 100644
--- a/matita/matita/contribs/lambdadelta/basic_2/static/sd.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/static/sd.ma
@@ -19,110 +19,113 @@ include "basic_2/static/sh.ma".
 (* sort degree specification *)
 record sd (h:sh): Type[0] ≝ {
    deg      : relation nat;                            (* degree of the sort *)
-   deg_total: ∀k. ∃l. deg k l;                         (* functional relation axioms *)
-   deg_mono : ∀k,l1,l2. deg k l1 → deg k l2 → l1 = l2;
-   deg_next : ∀k,l. deg k l → deg (next h k) (l - 1)   (* compatibility condition *)
+   deg_total: ∀k. ∃d. deg k d;                         (* functional relation axioms *)
+   deg_mono : ∀k,d1,d2. deg k d1 → deg k d2 → d1 = d2;
+   deg_next : ∀k,d. deg k d → deg (next h k) (d - 1)   (* compatibility condition *)
 }.
 
 (* Notable specifications ***************************************************)
 
-definition deg_O: relation nat ≝ λk,l. l = 0.
+definition deg_O: relation nat ≝ λk,d. d = 0.
 
 definition sd_O: ∀h. sd h ≝ λh. mk_sd h deg_O ….
-// /2 width=1/ /2 width=2/ qed.
+/2 width=2 by le_n_O_to_eq, le_n, ex_intro/ defined.
 
 inductive deg_SO (h:sh) (k:nat) (k0:nat): predicate nat ≝
-| deg_SO_pos : ∀l0. (next h)^l0 k0 = k → deg_SO h k k0 (l0 + 1)
-| deg_SO_zero: ((∃l0. (next h)^l0 k0 = k) → ⊥) → deg_SO h k k0 0
+| deg_SO_pos : ∀d0. (next h)^d0 k0 = k → deg_SO h k k0 (d0 + 1)
+| deg_SO_zero: ((∃d0. (next h)^d0 k0 = k) → ⊥) → deg_SO h k k0 0
 .
 
-fact deg_SO_inv_pos_aux: ∀h,k,k0,l0. deg_SO h k k0 l0 → ∀l. l0 = l + 1 →
-                         (next h)^l k0 = k.
-#h #k #k0 #l0 * -l0
-[ #l0 #Hl0 #l #H
+fact deg_SO_inv_pos_aux: ∀h,k,k0,d0. deg_SO h k k0 d0 → ∀d. d0 = d + 1 →
+                         (next h)^d k0 = k.
+#h #k #k0 #d0 * -d0
+[ #d0 #Hd0 #d #H
   lapply (injective_plus_l … H) -H #H destruct //
-| #_ #l0 <plus_n_Sm #H destruct
+| #_ #d0 <plus_n_Sm #H destruct
 ]
 qed.
 
-lemma deg_SO_inv_pos: ∀h,k,k0,l0. deg_SO h k k0 (l0 + 1) → (next h)^l0 k0 = k.
-/2 width=3/ qed-.
+lemma deg_SO_inv_pos: ∀h,k,k0,d0. deg_SO h k k0 (d0 + 1) → (next h)^d0 k0 = k.
+/2 width=3 by deg_SO_inv_pos_aux/ qed-.
 
 lemma deg_SO_refl: ∀h,k. deg_SO h k k 1.
 #h #k @(deg_SO_pos … 0 ?) //
 qed.
 
 lemma deg_SO_gt: ∀h,k1,k2. k1 < k2 → deg_SO h k1 k2 0.
-#h #k1 #k2 #HK12 @deg_SO_zero * #l elim l -l normalize
+#h #k1 #k2 #HK12 @deg_SO_zero * #d elim d -d normalize
 [ #H destruct
   elim (lt_refl_false … HK12)
-| #l #_ #H
-  lapply (next_lt h ((next h)^l k2)) >H -H #H
+| #d #_ #H
+  lapply (next_lt h ((next h)^d k2)) >H -H #H
   lapply (transitive_lt … H HK12) -k1 #H1
-  lapply (nexts_le h k2 l) #H2
-  lapply (le_to_lt_to_lt … H2 H1) -h -l #H
+  lapply (nexts_le h k2 d) #H2
+  lapply (le_to_lt_to_lt … H2 H1) -h -d #H
   elim (lt_refl_false … H)
+]
 qed.
 
 definition sd_SO: ∀h. nat → sd h ≝ λh,k. mk_sd h (deg_SO h k) ….
 [ #k0
-  lapply (nexts_dec h k0 k) * [ * /3 width=2/ | /4 width=2/ ]
-| #K0 #l1 #l2 * [ #l01 ] #H1 * [1,3: #l02 ] #H2 //
+  lapply (nexts_dec h k0 k) *
+  [ * /3 width=2 by deg_SO_pos, ex_intro/ | /4 width=2 by deg_SO_zero, ex_intro/ ]
+| #K0 #d1 #d2 * [ #d01 ] #H1 * [1,3: #d02 ] #H2 //
   [ < H2 in H1; -H2 #H
     lapply (nexts_inj … H) -H #H destruct //
-  | elim (H1 ?) /2 width=2/
-  | elim (H2 ?) /2 width=2/
+  | elim H1 /2 width=2 by ex_intro/
+  | elim H2 /2 width=2 by ex_intro/
   ]
-| #k0 #l0 *
-  [ #l #H destruct elim l -l normalize /2 width=1/
-  | #H1 @deg_SO_zero * #l #H2 destruct
-    @H1 -H1 @(ex_intro … (S l)) /2 width=1/ (**) (* explicit constructor *)
+| #k0 #d0 *
+  [ #d #H destruct elim d -d normalize
+    /2 width=1 by deg_SO_gt, deg_SO_pos, next_lt/
+  | #H1 @deg_SO_zero * #d #H2 destruct
+    @H1 -H1 @(ex_intro … (S d)) /2 width=1 by sym_eq/ (**) (* explicit constructor *)
   ]
 ]
-qed.
+defined.
 
-let rec sd_l (h:sh) (k:nat) (l:nat) on l : sd h ≝
-   match l with
+let rec sd_d (h:sh) (k:nat) (d:nat) on d : sd h ≝
+   match d with
    [ O   ⇒ sd_O h
-   | S l ⇒ match l with
+   | S d ⇒ match d with
            [ O ⇒ sd_SO h k
-           | _ ⇒ sd_l h (next h k) l
+           | _ ⇒ sd_d h (next h k) d
            ]
    ].
 
 (* Basic inversion lemmas ***************************************************)
 
-lemma deg_inv_pred: ∀h,g,k,l. deg h g (next h k) (l+1) → deg h g k (l+2).
-#h #g #k #l #H1
-elim (deg_total h g k) #l0 #H0
+lemma deg_inv_pred: ∀h,g,k,d. deg h g (next h k) (d+1) → deg h g k (d+2).
+#h #g #k #d #H1
+elim (deg_total h g k) #d0 #H0
 lapply (deg_next … H0) #H2
 lapply (deg_mono … H1 H2) -H1 -H2 #H
-<(associative_plus l 1 1) >H <plus_minus_m_m // /2 width=3 by transitive_le/
+<(associative_plus d 1 1) >H <plus_minus_m_m /2 width=3 by transitive_le/
 qed-.
 
-lemma deg_inv_prec: ∀h,g,k,l,l0. deg h g ((next h)^l k) (l0+1) → deg h g k (l+l0+1).
-#h #g #k #l @(nat_ind_plus … l) -l //
-#l #IHl #l0 >iter_SO #H
-lapply (deg_inv_pred … H) -H <(associative_plus l0 1 1) #H
-lapply (IHl … H) -IHl -H //
+lemma deg_inv_prec: ∀h,g,k,d,d0. deg h g ((next h)^d k) (d0+1) → deg h g k (d+d0+1).
+#h #g #k #d @(nat_ind_plus … d) -d //
+#d #IHd #d0 >iter_SO #H
+lapply (deg_inv_pred … H) -H <(associative_plus d0 1 1) #H
+lapply (IHd … H) -IHd -H //
 qed-.
 
 (* Basic properties *********************************************************)
 
-lemma deg_iter: ∀h,g,k,l1,l2. deg h g k l1 → deg h g ((next h)^l2 k) (l1-l2).
-#h #g #k #l1 #l2 @(nat_ind_plus … l2) -l2  [ <minus_n_O // ]
-#l2 #IHl2 #Hkl1 >iter_SO <minus_plus /3 width=1/
+lemma deg_iter: ∀h,g,k,d1,d2. deg h g k d1 → deg h g ((next h)^d2 k) (d1-d2).
+#h #g #k #d1 #d2 @(nat_ind_plus … d2) -d2  [ <minus_n_O // ]
+#d2 #IHd2 #Hkd1 >iter_SO <minus_plus /3 width=1 by deg_next/
 qed.
 
-lemma deg_next_SO: ∀h,g,k,l. deg h g k (l+1) → deg h g (next h k) l.
-#h #g #k #l #Hkl
-lapply (deg_next … Hkl) -Hkl <minus_plus_m_m //
+lemma deg_next_SO: ∀h,g,k,d. deg h g k (d+1) → deg h g (next h k) d.
+#h #g #k #d #Hkd
+lapply (deg_next … Hkd) -Hkd <minus_plus_m_m //
 qed-.
 
-lemma sd_l_SS: ∀h,k,l. sd_l h k (l + 2) = sd_l h (next h k) (l + 1).
-#h #k #l <plus_n_Sm <plus_n_Sm //
+lemma sd_d_SS: ∀h,k,d. sd_d h k (d + 2) = sd_d h (next h k) (d + 1).
+#h #k #d <plus_n_Sm <plus_n_Sm //
 qed.
 
-lemma sd_l_correct: ∀h,l,k. deg h (sd_l h k l) k l.
-#h #l @(nat_ind_plus … l) -l // #l @(nat_ind_plus … l) -l // /3 width=1 by deg_inv_pred/
+lemma sd_d_correct: ∀h,d,k. deg h (sd_d h k d) k d.
+#h #d @(nat_ind_plus … d) -d // #d @(nat_ind_plus … d) -d /3 width=1 by deg_inv_pred/
 qed.