theorem lpx_sn_conf: ∀R1,R2. lpx_sn_confluent R1 R2 →
confluent2 … (lpx_sn R1) (lpx_sn R2).
-#R1 #R2 #HR12 #L0 @(f_ind … length … L0) -L0 #x #IH *
+#R1 #R2 #HR12 #L0 @(ynat_f_ind … length … L0) -L0 #x #IH *
[ #_ #X1 #H1 #X2 #H2 -x
>(lpx_sn_inv_atom1 … H1) -X1
>(lpx_sn_inv_atom1 … H2) -X2 /2 width=3 by lpx_sn_atom, ex2_intro/
| #L0 #I #V0 #Hx #X1 #H1 #X2 #H2 destruct
elim (lpx_sn_inv_pair1 … H1) -H1 #L1 #V1 #HL01 #HV01 #H destruct
elim (lpx_sn_inv_pair1 … H2) -H2 #L2 #V2 #HL02 #HV02 #H destruct
- elim (IH … HL01 … HL02) -IH normalize // #L #HL1 #HL2
+ elim (IH … HL01 … HL02) -IH /2 width=2 by ylt_succ2_refl/ #L #HL1 #HL2
elim (HR12 … HV01 … HV02 … HL01 … HL02) -L0 -V0 /3 width=5 by lpx_sn_pair, ex2_intro/
]
qed-.