X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground_2%2Flib%2Fstar.ma;h=e8d881af0ad899b7279866481589f546e645f905;hb=1fd63df4c77f5c24024769432ea8492748b4ac79;hp=e5b7887667a0db4a958079569074a45af397ca60;hpb=50001ac0b45a3f6376e8cbfd9200149a01d68148;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/ground_2/lib/star.ma b/matita/matita/contribs/lambdadelta/ground_2/lib/star.ma
index e5b788766..e8d881af0 100644
--- a/matita/matita/contribs/lambdadelta/ground_2/lib/star.ma
+++ b/matita/matita/contribs/lambdadelta/ground_2/lib/star.ma
@@ -13,48 +13,28 @@
 (**************************************************************************)
 
 include "basics/star1.ma".
-include "ground_2/xoa/xoa_props.ma".
+include "ground_2/lib/relations.ma".
 
-(* PROPERTIES OF RELATIONS **************************************************)
+(* TRANSITIVE CLOSURE *******************************************************)
 
-definition Decidable: Prop → Prop ≝ λR. R ∨ (R → ⊥).
-
-definition Transitive: ∀A. ∀R: relation A. Prop ≝ λA,R.
-                       ∀a1,a0. R a1 a0 → ∀a2. R a0 a2 → R a1 a2.
-
-definition confluent2: ∀A. ∀R1,R2: relation A. Prop ≝ λA,R1,R2.
-                       ∀a0,a1. R1 a0 a1 → ∀a2. R2 a0 a2 →
-                       ∃∃a. R2 a1 a & R1 a2 a.
-
-definition transitive2: ∀A. ∀R1,R2: relation A. Prop ≝ λA,R1,R2.
-                        ∀a1,a0. R1 a1 a0 → ∀a2. R2 a0 a2 →
-                        ∃∃a. R2 a1 a & R1 a a2.
-
-definition bi_confluent:  ∀A,B. ∀R: bi_relation A B. Prop ≝ λA,B,R.
-                          ∀a0,a1,b0,b1. R a0 b0 a1 b1 → ∀a2,b2. R a0 b0 a2 b2 →
-                          ∃∃a,b. R a1 b1 a b & R a2 b2 a b.
-
-definition LTC: ∀A:Type[0]. ∀B. (A→relation B) → (A→relation B) ≝
+definition CTC: ∀A:Type[0]. ∀B. (A→relation B) → (A→relation B) ≝
                 λA,B,R,a. TC … (R a).
 
-definition lsub_trans: ∀A,B. relation2 (A→relation B) (relation A) ≝ λA,B,R1,R2.
-                       ∀L2,T1,T2. R1 L2 T1 T2 → ∀L1. R2 L1 L2 → R1 L1 T1 T2.
-
-definition s_r_trans: ∀A,B. relation2 (A→relation B) (relation A) ≝ λA,B,R1,R2.
-                      ∀L2,T1,T2. R1 L2 T1 T2 → ∀L1. R2 L1 L2 → LTC … R1 L1 T1 T2.
+definition s_r_transitive: ∀A,B. relation2 (A→relation B) (B→relation A) ≝ λA,B,R1,R2.
+                           ∀L2,T1,T2. R1 L2 T1 T2 → ∀L1. R2 T1 L1 L2 → CTC … R1 L1 T1 T2.
 
-definition s_rs_trans: ∀A,B. relation2 (A→relation B) (relation A) ≝ λA,B,R1,R2.
-                       ∀L2,T1,T2. LTC … R1 L2 T1 T2 → ∀L1. R2 L1 L2 → LTC … R1 L1 T1 T2.
+definition s_rs_transitive: ∀A,B. relation2 (A→relation B) (B→relation A) ≝ λA,B,R1,R2.
+                            ∀L2,T1,T2. CTC … R1 L2 T1 T2 → ∀L1. R2 T1 L1 L2 → CTC … R1 L1 T1 T2.
 
 lemma TC_strip1: ∀A,R1,R2. confluent2 A R1 R2 →
                  ∀a0,a1. TC … R1 a0 a1 → ∀a2. R2 a0 a2 →
                  ∃∃a. R2 a1 a & TC … R1 a2 a.
 #A #R1 #R2 #HR12 #a0 #a1 #H elim H -a1
 [ #a1 #Ha01 #a2 #Ha02
-  elim (HR12 … Ha01 … Ha02) -HR12 -a0 /3 width=3/
+  elim (HR12 … Ha01 … Ha02) -HR12 -a0 /3 width=3 by inj, ex2_intro/
 | #a #a1 #_ #Ha1 #IHa0 #a2 #Ha02
   elim (IHa0 … Ha02) -a0 #a0 #Ha0 #Ha20
-  elim (HR12 … Ha1 … Ha0) -HR12 -a /4 width=5/
+  elim (HR12 … Ha1 … Ha0) -HR12 -a /4 width=5 by step, ex2_intro/
 ]
 qed.
 
@@ -63,10 +43,10 @@ lemma TC_strip2: ∀A,R1,R2. confluent2 A R1 R2 →
                  ∃∃a. TC … R2 a1 a & R1 a2 a.
 #A #R1 #R2 #HR12 #a0 #a2 #H elim H -a2
 [ #a2 #Ha02 #a1 #Ha01
-  elim (HR12 … Ha01 … Ha02) -HR12 -a0 /3 width=3/
+  elim (HR12 … Ha01 … Ha02) -HR12 -a0 /3 width=3 by inj, ex2_intro/
 | #a #a2 #_ #Ha2 #IHa0 #a1 #Ha01
   elim (IHa0 … Ha01) -a0 #a0 #Ha10 #Ha0
-  elim (HR12 … Ha0 … Ha2) -HR12 -a /4 width=3/
+  elim (HR12 … Ha0 … Ha2) -HR12 -a /4 width=3 by step, ex2_intro/
 ]
 qed.
 
@@ -74,10 +54,10 @@ lemma TC_confluent2: ∀A,R1,R2.
                      confluent2 A R1 R2 → confluent2 A (TC … R1) (TC … R2).
 #A #R1 #R2 #HR12 #a0 #a1 #H elim H -a1
 [ #a1 #Ha01 #a2 #Ha02
-  elim (TC_strip2 … HR12 … Ha02 … Ha01) -HR12 -a0 /3 width=3/
+  elim (TC_strip2 … HR12 … Ha02 … Ha01) -HR12 -a0 /3 width=3 by inj, ex2_intro/
 | #a #a1 #_ #Ha1 #IHa0 #a2 #Ha02
   elim (IHa0 … Ha02) -a0 #a0 #Ha0 #Ha20
-  elim (TC_strip2 … HR12 … Ha0 … Ha1) -HR12 -a /4 width=5/
+  elim (TC_strip2 … HR12 … Ha0 … Ha1) -HR12 -a /4 width=5 by step, ex2_intro/
 ]
 qed.
 
@@ -86,10 +66,10 @@ lemma TC_strap1: ∀A,R1,R2. transitive2 A R1 R2 →
                  ∃∃a. R2 a1 a & TC … R1 a a2.
 #A #R1 #R2 #HR12 #a1 #a0 #H elim H -a0
 [ #a0 #Ha10 #a2 #Ha02
-  elim (HR12 … Ha10 … Ha02) -HR12 -a0 /3 width=3/
+  elim (HR12 … Ha10 … Ha02) -HR12 -a0 /3 width=3 by inj, ex2_intro/
 | #a #a0 #_ #Ha0 #IHa #a2 #Ha02
   elim (HR12 … Ha0 … Ha02) -HR12 -a0 #a0 #Ha0 #Ha02
-  elim (IHa … Ha0) -a /4 width=5/
+  elim (IHa … Ha0) -a /4 width=5 by step, ex2_intro/
 ]
 qed.
 
@@ -98,10 +78,10 @@ lemma TC_strap2: ∀A,R1,R2. transitive2 A R1 R2 →
                  ∃∃a. TC … R2 a1 a & R1 a a2.
 #A #R1 #R2 #HR12 #a0 #a2 #H elim H -a2
 [ #a2 #Ha02 #a1 #Ha10
-  elim (HR12 … Ha10 … Ha02) -HR12 -a0 /3 width=3/
+  elim (HR12 … Ha10 … Ha02) -HR12 -a0 /3 width=3 by inj, ex2_intro/
 | #a #a2 #_ #Ha02 #IHa #a1 #Ha10
   elim (IHa … Ha10) -a0 #a0 #Ha10 #Ha0
-  elim (HR12 … Ha0 … Ha02) -HR12 -a /4 width=3/
+  elim (HR12 … Ha0 … Ha02) -HR12 -a /4 width=3 by step, ex2_intro/
 ]
 qed.
 
@@ -109,77 +89,76 @@ lemma TC_transitive2: ∀A,R1,R2.
                       transitive2 A R1 R2 → transitive2 A (TC … R1) (TC … R2).
 #A #R1 #R2 #HR12 #a1 #a0 #H elim H -a0
 [ #a0 #Ha10 #a2 #Ha02
-  elim (TC_strap2 … HR12 … Ha02 … Ha10) -HR12 -a0 /3 width=3/
+  elim (TC_strap2 … HR12 … Ha02 … Ha10) -HR12 -a0 /3 width=3 by inj, ex2_intro/
 | #a #a0 #_ #Ha0 #IHa #a2 #Ha02
   elim (TC_strap2 … HR12 … Ha02 … Ha0) -HR12 -a0 #a0 #Ha0 #Ha02
-  elim (IHa … Ha0) -a /4 width=5/
+  elim (IHa … Ha0) -a /4 width=5 by step, ex2_intro/
 ]
 qed.
 
-definition NF: ∀A. relation A → relation A → predicate A ≝
-   λA,R,S,a1. ∀a2. R a1 a2 → S a2 a1.
-
-definition NF_dec: ∀A. relation A → relation A → Prop ≝
-                   λA,R,S. ∀a1. NF A R S a1 ∨
-                   ∃∃a2. R … a1 a2 & (S a2 a1 → ⊥).
-
-inductive SN (A) (R,S:relation A): predicate A ≝
-| SN_intro: ∀a1. (∀a2. R a1 a2 → (S a2 a1 → ⊥) → SN A R S a2) → SN A R S a1
-.
-
-lemma NF_to_SN: ∀A,R,S,a. NF A R S a → SN A R S a.
-#A #R #S #a1 #Ha1
-@SN_intro #a2 #HRa12 #HSa12
-elim HSa12 -HSa12 /2 width=1/
-qed.
+lemma CTC_lsub_trans: ∀A,B,R,S. lsub_trans A B R S → lsub_trans A B (CTC … R) S.
+#A #B #R #S #HRS #L2 #T1 #T2 #H elim H -T2 /3 width=3 by inj/
+#T #T2 #_ #HT2 #IHT1 #L1 #HL12
+lapply (HRS … HT2 … HL12) -HRS -HT2 /3 width=3 by step/
+qed-.
 
-lemma SN_to_NF: ∀A,R,S. NF_dec A R S →
-                ∀a1. SN A R S a1 →
-                ∃∃a2. star … R a1 a2 & NF A R S a2.
-#A #R #S #HRS #a1 #H elim H -a1
-#a1 #_ #IHa1 elim (HRS a1) -HRS /2 width=3/
-* #a0 #Ha10 #Ha01 elim (IHa1 … Ha10 Ha01) -IHa1 -Ha01 /3 width=3/
+lemma s_r_conf1_CTC1: ∀A,B,S,R. s_r_confluent1 A B S R → s_r_confluent1 A B (CTC … S) R.
+#A #B #S #R #HSR #L1 #T1 #T2 #H @(TC_ind_dx … T1 H) -T1 /3 width=3 by/
 qed-.
 
-definition NF_sn: ∀A. relation A → relation A → predicate A ≝
-   λA,R,S,a2. ∀a1. R a1 a2 → S a2 a1.
+lemma s_r_trans_CTC1: ∀A,B,S,R. s_r_confluent1 A B S R →
+                      s_r_transitive A B S R → s_rs_transitive A B S R.
+#A #B #S #R #H1SR #H2SR #L2 #T1 #T2 #H @(TC_ind_dx … T1 H) -T1 /2 width=3 by/
+#T1 #T #HT1 #_ #IHT2 #L1 #HL12 lapply (H2SR … HT1 … HL12) -H2SR -HT1
+/4 width=5 by s_r_conf1_CTC1, trans_TC/
+qed-.
 
-inductive SN_sn (A) (R,S:relation A): predicate A ≝
-| SN_sn_intro: ∀a2. (∀a1. R a1 a2 → (S a2 a1 → ⊥) → SN_sn A R S a1) → SN_sn A R S a2
-.
+lemma s_r_trans_CTC2: ∀A,B,S,R. s_rs_transitive A B S R → s_r_transitive A B S (CTC … R).
+#A #B #S #R #HSR #L2 #T1 #T2 #HT12 #L1 #H @(TC_ind_dx … L1 H) -L1 /3 width=3 by inj/
+qed-.
 
-lemma NF_to_SN_sn: ∀A,R,S,a. NF_sn A R S a → SN_sn A R S a.
-#A #R #S #a2 #Ha2
-@SN_sn_intro #a1 #HRa12 #HSa12
-elim HSa12 -HSa12 /2 width=1/
-qed.
+lemma s_r_to_s_rs_trans: ∀A,B,S,R. s_r_transitive A B (CTC … S) R →
+                         s_rs_transitive A B S R.
+#A #B #S #R #HSR #L2 #T1 #T2 #HL2 #L1 #HT1
+elim (TC_idem … (S L1) …  T1 T2)
+#_ #H @H @HSR //
+qed-.
 
-lemma TC_lsub_trans: ∀A,B,R,S. lsub_trans A B R S → lsub_trans A B (LTC … R) S.
-#A #B #R #S #HRS #L2 #T1 #T2 #H elim H -T2 [ /3 width=3/ ]
-#T #T2 #_ #HT2 #IHT1 #L1 #HL12
-lapply (HRS … HT2 … HL12) -HRS -HT2 /3 width=3/
+lemma s_rs_to_s_r_trans: ∀A,B,S,R. s_rs_transitive A B S R →
+                         s_r_transitive A B (CTC … S) R.
+#A #B #S #R #HSR #L2 #T1 #T2 #HL2 #L1 #HT1
+elim (TC_idem … (S L1) …  T1 T2)
+#H #_ @H @HSR //
 qed-.
 
-lemma s_r_trans_TC1: ∀A,B,R,S. s_r_trans A B R S → s_rs_trans A B R S.
-#A #B #R #S #HRS #L2 #T1 #T2 #H elim H -T2 [ /3 width=3/ ]
-#T #T2 #_ #HT2 #IHT1 #L1 #HL12
-lapply (HRS … HT2 … HL12) -HRS -HT2 /3 width=3/
+lemma s_rs_trans_TC1: ∀A,B,S,R. s_rs_transitive A B S R →
+                      s_rs_transitive A B (CTC … S) R.
+#A #B #S #R #HSR #L2 #T1 #T2 #HL2 #L1 #HT1
+elim (TC_idem … (S L1) …  T1 T2)
+elim (TC_idem … (S L2) …  T1 T2)
+#_ #H1 #H2 #_ @H2 @HSR /3 width=3 by/
 qed-.
 
-lemma s_r_trans_TC2: ∀A,B,R,S. s_rs_trans A B R S → s_r_trans A B R (TC … S).
-#A #B #R #S #HRS #L2 #T1 #T2 #HT12 #L1 #H @(TC_ind_dx … L1 H) -L1 /2 width=3/ /3 width=3/
+(* Normal form and strong normalization *************************************)
+
+lemma SN_to_NF: ∀A,R,S. NF_dec A R S →
+                ∀a1. SN A R S a1 →
+                ∃∃a2. star … R a1 a2 & NF A R S a2.
+#A #R #S #HRS #a1 #H elim H -a1
+#a1 #_ #IHa1 elim (HRS a1) -HRS /2 width=3 by srefl, ex2_intro/
+* #a0 #Ha10 #Ha01 elim (IHa1 … Ha10 Ha01) -IHa1 -Ha01 /3 width=3 by star_compl, ex2_intro/
 qed-.
 
-(* relations on unboxed pairs ***********************************************)
+(* Relations on unboxed pairs ***********************************************)
 
 lemma bi_TC_strip: ∀A,B,R. bi_confluent A B R →
                    ∀a0,a1,b0,b1. R a0 b0 a1 b1 → ∀a2,b2. bi_TC … R a0 b0 a2 b2 →
                    ∃∃a,b. bi_TC … R a1 b1 a b & R a2 b2 a b.
 #A #B #R #HR #a0 #a1 #b0 #b1 #H01 #a2 #b2 #H elim H -a2 -b2
 [ #a2 #b2 #H02
-  elim (HR … H01 … H02) -HR -a0 -b0 /3 width=4/
+  elim (HR … H01 … H02) -HR -a0 -b0 /3 width=4 by ex2_2_intro, bi_inj/
 | #a2 #b2 #a3 #b3 #_ #H23 * #a #b #H1 #H2
-  elim (HR … H23 … H2) -HR -a0 -b0 -a2 -b2 /3 width=4/
+  elim (HR … H23 … H2) -HR -a0 -b0 -a2 -b2 /3 width=4 by ex2_2_intro, bi_step/
 ]
 qed.
 
@@ -187,10 +166,10 @@ lemma bi_TC_confluent: ∀A,B,R. bi_confluent A B R →
                        bi_confluent A B (bi_TC … R).
 #A #B #R #HR #a0 #a1 #b0 #b1 #H elim H -a1 -b1
 [ #a1 #b1 #H01 #a2 #b2 #H02
-  elim (bi_TC_strip … HR … H01 … H02) -a0 -b0 /3 width=4/
+  elim (bi_TC_strip … HR … H01 … H02) -a0 -b0 /3 width=4 by ex2_2_intro, bi_inj/
 | #a1 #b1 #a3 #b3 #_ #H13 #IH #a2 #b2 #H02
   elim (IH … H02) -a0 -b0 #a0 #b0 #H10 #H20
-  elim (bi_TC_strip … HR … H13 … H10) -a1 -b1 /3 width=7/
+  elim (bi_TC_strip … HR … H13 … H10) -a1 -b1 /3 width=7 by ex2_2_intro, bi_step/
 ]
 qed.
 
@@ -198,7 +177,7 @@ lemma bi_TC_decomp_r: ∀A,B. ∀R:bi_relation A B.
                       ∀a1,a2,b1,b2. bi_TC … R a1 b1 a2 b2 →
                       R a1 b1 a2 b2 ∨
                       ∃∃a,b. bi_TC … R a1 b1 a b & R a b a2 b2.
-#A #B #R #a1 #a2 #b1 #b2 * -a2 -b2 /2 width=1/ /3 width=4/
+#A #B #R #a1 #a2 #b1 #b2 * -a2 -b2 /2 width=1/ /3 width=4 by ex2_2_intro, or_intror/
 qed-.
 
 lemma bi_TC_decomp_l: ∀A,B. ∀R:bi_relation A B.
@@ -206,41 +185,34 @@ lemma bi_TC_decomp_l: ∀A,B. ∀R:bi_relation A B.
                       R a1 b1 a2 b2 ∨
                       ∃∃a,b. R a1 b1 a b & bi_TC … R a b a2 b2.
 #A #B #R #a1 #a2 #b1 #b2 #H @(bi_TC_ind_dx … a1 b1 H) -a1 -b1
-[ /2 width=1/
-| #a1 #a #b1 #b #Hab1 #Hab2 #_ /3 width=4/
+[ /2 width=1 by or_introl/
+| #a1 #a #b1 #b #Hab1 #Hab2 #_ /3 width=4 by ex2_2_intro, or_intror/ (**) (* auto fails without #_ *)
 ]
 qed-.
 
-(* relations on unboxed triples *********************************************)
-
-definition tri_RC: ∀A,B,C. tri_relation A B C → tri_relation A B C ≝
-                   λA,B,C,R,a1,b1,c1,a2,b2,c2. R … a1 b1 c1 a2 b2 c2 ∨
-                   ∧∧ a1 = a2 & b1 = b2 & c1 = c2.
-
-lemma tri_RC_reflexive: ∀A,B,C,R. tri_reflexive A B C (tri_RC … R).
-/3 width=1/ qed.
+(* Relations on unboxed triples *********************************************)
 
 definition tri_star: ∀A,B,C,R. tri_relation A B C ≝
                      λA,B,C,R. tri_RC A B C (tri_TC … R).
 
 lemma tri_star_tri_reflexive: ∀A,B,C,R. tri_reflexive A B C (tri_star … R).
-/2 width=1/ qed.
+/2 width=1 by/ qed.
 
 lemma tri_TC_to_tri_star: ∀A,B,C,R,a1,b1,c1,a2,b2,c2.
                           tri_TC A B C R a1 b1 c1 a2 b2 c2 →
                           tri_star A B C R a1 b1 c1 a2 b2 c2.
-/2 width=1/ qed.
+/2 width=1 by or_introl/ qed.
 
 lemma tri_R_to_tri_star: ∀A,B,C,R,a1,b1,c1,a2,b2,c2.
                          R a1 b1 c1 a2 b2 c2 → tri_star A B C R a1 b1 c1 a2 b2 c2.
-/3 width=1/ qed.
+/3 width=1 by tri_TC_to_tri_star, tri_inj/ qed.
 
 lemma tri_star_strap1: ∀A,B,C,R,a1,a,a2,b1,b,b2,c1,c,c2.
                        tri_star A B C R a1 b1 c1 a b c →
                        R a b c a2 b2 c2 → tri_star A B C R a1 b1 c1 a2 b2 c2.
 #A #B #C #R #a1 #a #a2 #b1 #b #b2 #c1 #c #c2 *
-[ /3 width=5/
-| * #H1 #H2 #H3 destruct /2 width=1/
+[ /3 width=5 by tri_TC_to_tri_star, tri_step/
+| * #H1 #H2 #H3 destruct /2 width=1 by tri_R_to_tri_star/
 ]
 qed.
 
@@ -248,8 +220,8 @@ lemma tri_star_strap2: ∀A,B,C,R,a1,a,a2,b1,b,b2,c1,c,c2. R a1 b1 c1 a b c →
                        tri_star A B C R a b c a2 b2 c2 →
                        tri_star A B C R a1 b1 c1 a2 b2 c2.
 #A #B #C #R #a1 #a #a2 #b1 #b #b2 #c1 #c #c2 #H *
-[ /3 width=5/
-| * #H1 #H2 #H3 destruct /2 width=1/
+[ /3 width=5 by tri_TC_to_tri_star, tri_TC_strap/
+| * #H1 #H2 #H3 destruct /2 width=1 by tri_R_to_tri_star/
 ]
 qed.
 
@@ -258,8 +230,8 @@ lemma tri_star_to_tri_TC_to_tri_TC: ∀A,B,C,R,a1,a,a2,b1,b,b2,c1,c,c2.
                                     tri_TC A B C R a b c a2 b2 c2 →
                                     tri_TC A B C R a1 b1 c1 a2 b2 c2.
 #A #B #C #R #a1 #a #a2 #b1 #b #b2 #c1 #c #c2 *
-[ /2 width=5/
-| * #H1 #H2 #H3 destruct /2 width=1/
+[ /2 width=5 by tri_TC_transitive/
+| * #H1 #H2 #H3 destruct /2 width=1 by/
 ]
 qed.
 
@@ -268,15 +240,15 @@ lemma tri_TC_to_tri_star_to_tri_TC: ∀A,B,C,R,a1,a,a2,b1,b,b2,c1,c,c2.
                                     tri_star A B C R a b c a2 b2 c2 →
                                     tri_TC A B C R a1 b1 c1 a2 b2 c2.
 #A #B #C #R #a1 #a #a2 #b1 #b #b2 #c1 #c #c2 #H *
-[ /2 width=5/
-| * #H1 #H2 #H3 destruct /2 width=1/
+[ /2 width=5 by tri_TC_transitive/
+| * #H1 #H2 #H3 destruct /2 width=1 by/
 ]
 qed.
 
 lemma tri_tansitive_tri_star: ∀A,B,C,R. tri_transitive A B C (tri_star … R).
 #A #B #C #R #a1 #a #b1 #b #c1 #c #H #a2 #b2 #c2 *
-[ /3 width=5/
-| * #H1 #H2 #H3 destruct /2 width=1/
+[ /3 width=5 by tri_star_to_tri_TC_to_tri_TC, tri_TC_to_tri_star/
+| * #H1 #H2 #H3 destruct /2 width=1 by/
 ]
 qed.
 
@@ -284,7 +256,7 @@ lemma tri_star_ind: ∀A,B,C,R,a1,b1,c1. ∀P:relation3 A B C. P a1 b1 c1 →
                     (∀a,a2,b,b2,c,c2. tri_star … R a1 b1 c1 a b c → R a b c a2 b2 c2 → P a b c → P a2 b2 c2) →
                     ∀a2,b2,c2. tri_star … R a1 b1 c1 a2 b2 c2 → P a2 b2 c2.
 #A #B #C #R #a1 #b1 #c1 #P #H #IH #a2 #b2 #c2 *
-[ #H12 elim H12 -a2 -b2 -c2 /2 width=6/ -H /3 width=6/
+[ #H12 elim H12 -a2 -b2 -c2 /3 width=6 by tri_TC_to_tri_star/
 | * #H1 #H2 #H3 destruct //
 ]
 qed-.
@@ -293,7 +265,7 @@ lemma tri_star_ind_dx: ∀A,B,C,R,a2,b2,c2. ∀P:relation3 A B C. P a2 b2 c2 →
                        (∀a1,a,b1,b,c1,c. R a1 b1 c1 a b c → tri_star … R a b c a2 b2 c2 → P a b c → P a1 b1 c1) →
                        ∀a1,b1,c1. tri_star … R a1 b1 c1 a2 b2 c2 → P a1 b1 c1.
 #A #B #C #R #a2 #b2 #c2 #P #H #IH #a1 #b1 #c1 *
-[ #H12 @(tri_TC_ind_dx … a1 b1 c1 H12) -a1 -b1 -c1 /2 width=6/ -H /3 width=6/
+[ #H12 @(tri_TC_ind_dx … a1 b1 c1 H12) -a1 -b1 -c1 /3 width=6 by tri_TC_to_tri_star/
 | * #H1 #H2 #H3 destruct //
 ]
 qed-.