(* DEGREE-BASED EQUIVALENCE FOR CLOSURES ON REFERRED ENTRIES ****************)
+(* Advanced properties ******************************************************)
+
+lemma ffdeq_sym: ∀h,o. tri_symmetric … (ffdeq h o).
+#h #o #G1 #G2 #L1 #L2 #T1 #T2 * -G1 -L1 -T1
+/3 width=1 by ffdeq_intro_dx, lfdeq_sym, tdeq_sym/
+qed-.
+
(* Main properties **********************************************************)
theorem ffdeq_trans: ∀h,o. tri_transitive … (ffdeq h o).
#h #o #G1 #G #L1 #L #T1 #T * -G -L -T
-#L #HL1 #G2 #L2 #T2 * -G2 -L2 -T2 /3 width=3 by ffdeq_intro, lfdeq_trans/
+#L #T #HL1 #HT1 #G2 #L2 #T2 * -G2 -L2 -T2
+/4 width=5 by ffdeq_intro_sn, lfdeq_trans, tdeq_lfdeq_div, tdeq_trans/
qed-.
theorem ffdeq_canc_sn: ∀h,o,G,G1,G2,L,L1,L2,T,T1,T2.