--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| The HELM team. *)
+(* ||A|| http://helm.cs.unibo.it *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU General Public License Version 2 *)
+(* *)
+(**************************************************************************)
+
+include "basic_2/reduction/lpx_lpx.ma".
+include "basic_2/reduction/fpn.ma".
+
+(* REDUCTION FOR "BIG TREE" NORMAL FORMS ************************************)
+
+(* Advanced properties ******************************************************)
+
+lemma fpn_fqu_trans: ∀h,g,F1,G1,K1,L1,V1,T1. ⦃F1, K1, V1⦄ ⊢ ⋕➡[h, g] ⦃G1, L1, T1⦄ →
+ ∀G2,L2,T2. ⦃G1, L1, T1⦄ ⊃ ⦃G2, L2, T2⦄ →
+ ∃∃F2,K2,V2. ⦃F1, K1, V1⦄ ⊃ ⦃F2, K2, V2⦄ & ⦃F2, K2, V2⦄ ⊢ ⋕➡[h, g] ⦃G2, L2, T2⦄.
+#h #g #F1 #G1 #K1 #L1 #V1 #T1 * -G1 -L1 -T1
+#L1 #HKL1 #HV1 #G2 #L2 #T2 #H12 elim (lpx_lleq_fqu_trans … H12 … HKL1 HV1) -L1
+/3 width=5 by fpn_intro, ex2_3_intro/
+qed-.
+
+lemma fpn_fquq_trans: ∀h,g,F1,G1,K1,L1,V1,T1. ⦃F1, K1, V1⦄ ⊢ ⋕➡[h, g] ⦃G1, L1, T1⦄ →
+ ∀G2,L2,T2. ⦃G1, L1, T1⦄ ⊃⸮ ⦃G2, L2, T2⦄ →
+ ∃∃F2,K2,V2. ⦃F1, K1, V1⦄ ⊃⸮ ⦃F2, K2, V2⦄ & ⦃F2, K2, V2⦄ ⊢ ⋕➡[h, g] ⦃G2, L2, T2⦄.
+#h #g #F1 #G1 #K1 #L1 #V1 #T1 * -G1 -L1 -T1
+#L1 #HKL1 #HV1 #G2 #L2 #T2 #H12 elim (lpx_lleq_fquq_trans … H12 … HKL1 HV1) -L1
+/3 width=5 by fpn_intro, ex2_3_intro/
+qed-.
+
+lemma fpn_fqup_trans: ∀h,g,F1,G1,K1,L1,V1,T1. ⦃F1, K1, V1⦄ ⊢ ⋕➡[h, g] ⦃G1, L1, T1⦄ →
+ ∀G2,L2,T2. ⦃G1, L1, T1⦄ ⊃+ ⦃G2, L2, T2⦄ →
+ ∃∃F2,K2,V2. ⦃F1, K1, V1⦄ ⊃+ ⦃F2, K2, V2⦄ & ⦃F2, K2, V2⦄ ⊢ ⋕➡[h, g] ⦃G2, L2, T2⦄.
+#h #g #F1 #G1 #K1 #L1 #V1 #T1 * -G1 -L1 -T1
+#L1 #HKL1 #HV1 #G2 #L2 #T2 #H12 elim (lpx_lleq_fqup_trans … H12 … HKL1 HV1) -L1
+/3 width=5 by fpn_intro, ex2_3_intro/
+qed-.
+
+lemma fpn_fqus_trans: ∀h,g,F1,G1,K1,L1,V1,T1. ⦃F1, K1, V1⦄ ⊢ ⋕➡[h, g] ⦃G1, L1, T1⦄ →
+ ∀G2,L2,T2. ⦃G1, L1, T1⦄ ⊃* ⦃G2, L2, T2⦄ →
+ ∃∃F2,K2,V2. ⦃F1, K1, V1⦄ ⊃* ⦃F2, K2, V2⦄ & ⦃F2, K2, V2⦄ ⊢ ⋕➡[h, g] ⦃G2, L2, T2⦄.
+#h #g #F1 #G1 #K1 #L1 #V1 #T1 * -G1 -L1 -T1
+#L1 #HKL1 #HV1 #G2 #L2 #T2 #H12 elim (lpx_lleq_fqus_trans … H12 … HKL1 HV1) -L1
+/3 width=5 by fpn_intro, ex2_3_intro/
+qed-.