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3 (*      ||M||                                                             *)
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14
15 include "delayed_updating/reduction/ifr.ma".
16
17 include "delayed_updating/substitution/fsubst_lift.ma".
18 include "delayed_updating/substitution/fsubst_eq.ma".
19 include "delayed_updating/substitution/lift_prototerm_after.ma".
20 include "delayed_updating/substitution/lift_path_head.ma".
21 include "delayed_updating/substitution/lift_rmap_head.ma".
22
23 include "ground/relocation/tr_uni_compose.ma".
24 include "ground/relocation/tr_compose_eq.ma".
25
26 (* IMMEDIATE FOCUSED REDUCTION **********************************************)
27
28 (* Constructions with lift **************************************************)
29
30 theorem ifr_lift_bi (f) (t1) (t2) (r):
31         t1 ➡𝐢𝐟[r] t2 → ↑[f]t1 ➡𝐢𝐟[↑[f]r] ↑[f]t2.
32 #f #t1 #t2 #r
33 * #p #q #k #Hr #H1k #Ht1 #Ht2 destruct
34 @(ex4_3_intro … (↑[f]p) (↑[↑[p◖𝗔◖𝗟]f]q) ((↑[p●𝗔◗𝗟◗q]f)@⧣❨k❩))
35 [ -H1k -Ht1 -Ht2 //
36 | -Ht1 -Ht2
37   <lift_rmap_L_dx >lift_path_L_sn
38   <(lift_path_head_closed … H1k) in ⊢ (??%?); -H1k //
39 | lapply (in_comp_lift_path_term f … Ht1) -Ht2 -Ht1 -H1k
40   <lift_path_d_dx #Ht1 //
41 | lapply (lift_term_eq_repl_dx f … Ht2) -Ht2 #Ht2 -Ht1
42   @(subset_eq_trans … Ht2) -t2
43   @(subset_eq_trans … (lift_term_fsubst …))
44   @fsubst_eq_repl [ // | <lift_path_append // ]
45   @(subset_eq_canc_sn … (lift_term_eq_repl_dx …))
46   [ @lift_term_grafted_S | skip ]
47   @(subset_eq_trans … (lift_term_after …))
48   @(subset_eq_canc_dx … (lift_term_after …))
49   @lift_term_eq_repl_sn
50 (* Note: crux of the proof begins *)
51   @(stream_eq_trans … (tr_compose_uni_dx …))
52   @tr_compose_eq_repl //
53   >list_append_rcons_sn in H1k; #H1k >lift_rmap_A_dx
54   /2 width=1 by tls_lift_rmap_closed/
55 (* Note: crux of the proof ends *)
56 ]
57 qed.