∀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) ≝
+ λA,B,R,a. TC … (R a).
+
+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_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.
+
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.
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/
+elim HSa12 -HSa12 /2 width=1/
qed.
definition NF_sn: ∀A. relation A → relation A → predicate A ≝
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/
+elim HSa12 -HSa12 /2 width=1/
qed.
lemma bi_TC_strip: ∀A,B,R. bi_confluent A B R →
∀a1,a2,b1,b2. bi_TC … R a1 b1 a2 b2 →
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 ?????????? H) -a1 -b1
+#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/
]
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/
+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/
+qed-.