-theorem dfr_des_ifr (f) (p) (q) (t1) (t2): t1 Ļµ š ā
- t1 ā”šš[p,q] t2 ā ā¼[f]t1 ā”š¢š[āp,āq] ā¼[f]t2.
-#f #p #q #t1 #t2 #H0t1
-* #n * #H1n #Ht1 #Ht2
-@(ex_intro ā¦ (āāq)) @and3_intro
-[ -H0t1 -Ht1 -Ht2
- >structure_L_sn >structure_reverse
- >H1n in ā¢ (??%?); >path_head_structure_depth <H1n -H1n //
+theorem dfr_des_ifr (f) (t1) (t2) (r): t1 Ļµ š ā
+ t1 ā”šš[r] t2 ā ā¼[f]t1 ā”š¢š[ār] ā¼[f]t2.
+#f #t1 #t2 #r #H0t1
+* #p #q #k #Hr #H1k #Ht1 #Ht2 destruct
+@(ex4_3_intro ā¦ (āp) (āq) (āāq))
+[ -H0t1 -H1k -Ht1 -Ht2 //
+| -H0t1 -Ht1 -Ht2
+ >structure_L_sn
+ >H1k in ā¢ (??%?); >path_head_structure_depth <H1k -H1k //