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Theorem dfrdg2 36527
Description: Alternate definition of the recursive function generator when 𝐼 is a set. (Contributed by Scott Fenton, 26-Mar-2014.) (Revised by Mario Carneiro, 19-Apr-2014.)
Assertion
Ref Expression
dfrdg2 (𝐼 ∈ 𝑉 → rec(𝐹, 𝐼) = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))})
Distinct variable groups:   𝑓,𝐹,𝑥,𝑦   𝑓,𝐼,𝑥,𝑦
Allowed substitution hints:   𝑉(𝑥, 𝑦, 𝑓)

Proof of Theorem dfrdg2
Dummy variables 𝑔 𝑖 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 rdgeq2 8404 . . 3 (𝑖 = 𝐼 → rec(𝐹, 𝑖) = rec(𝐹, 𝐼))
2 ifeq1 4486 . . . . . . . . 9 (𝑖 = 𝐼 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
32eqeq2d 2772 . . . . . . . 8 (𝑖 = 𝐼 → ((𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) ↔ (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
43ralbidv 3186 . . . . . . 7 (𝑖 = 𝐼 → (∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) ↔ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
54anbi2d 642 . . . . . 6 (𝑖 = 𝐼 → ((𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))) ↔ (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))))
65rexbidv 3187 . . . . 5 (𝑖 = 𝐼 → (∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))) ↔ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))))
76abbidv 2827 . . . 4 (𝑖 = 𝐼 → {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))} = {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))})
87unieqd 4880 . . 3 (𝑖 = 𝐼 → ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))} = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))})
91, 8eqeq12d 2777 . 2 (𝑖 = 𝐼 → (rec(𝐹, 𝑖) = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))} ↔ rec(𝐹, 𝐼) = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))}))
10 df-rdg 8402 . . 3 rec(𝐹, 𝑖) = recs((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔))))))
11 dfrecs3 8364 . . 3 recs((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))) = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)))}
12 vex 3455 . . . . . . . . . . . . 13 𝑓 ∈ V
1312resex 6020 . . . . . . . . . . . 12 (𝑓 ↾ 𝑦) ∈ V
14 eqeq1 2765 . . . . . . . . . . . . . . 15 (𝑔 = (𝑓 ↾ 𝑦) → (𝑔 = ∅ ↔ (𝑓 ↾ 𝑦) = ∅))
15 relres 5996 . . . . . . . . . . . . . . . 16 Rel (𝑓 ↾ 𝑦)
16 reldm0 5910 . . . . . . . . . . . . . . . 16 (Rel (𝑓 ↾ 𝑦) → ((𝑓 ↾ 𝑦) = ∅ ↔ dom (𝑓 ↾ 𝑦) = ∅))
1715, 16ax-mp 5 . . . . . . . . . . . . . . 15 ((𝑓 ↾ 𝑦) = ∅ ↔ dom (𝑓 ↾ 𝑦) = ∅)
1814, 17bitrdi 290 . . . . . . . . . . . . . 14 (𝑔 = (𝑓 ↾ 𝑦) → (𝑔 = ∅ ↔ dom (𝑓 ↾ 𝑦) = ∅))
19 dmeq 5885 . . . . . . . . . . . . . . . 16 (𝑔 = (𝑓 ↾ 𝑦) → dom 𝑔 = dom (𝑓 ↾ 𝑦))
20 limeq 6367 . . . . . . . . . . . . . . . 16 (dom 𝑔 = dom (𝑓 ↾ 𝑦) → (Lim dom 𝑔 ↔ Lim dom (𝑓 ↾ 𝑦)))
2119, 20syl 18 . . . . . . . . . . . . . . 15 (𝑔 = (𝑓 ↾ 𝑦) → (Lim dom 𝑔 ↔ Lim dom (𝑓 ↾ 𝑦)))
22 rneq 5918 . . . . . . . . . . . . . . . . 17 (𝑔 = (𝑓 ↾ 𝑦) → ran 𝑔 = ran (𝑓 ↾ 𝑦))
23 df-ima 5664 . . . . . . . . . . . . . . . . 17 (𝑓 “ 𝑦) = ran (𝑓 ↾ 𝑦)
2422, 23eqtr4di 2814 . . . . . . . . . . . . . . . 16 (𝑔 = (𝑓 ↾ 𝑦) → ran 𝑔 = (𝑓 “ 𝑦))
2524unieqd 4880 . . . . . . . . . . . . . . 15 (𝑔 = (𝑓 ↾ 𝑦) → ∪ ran 𝑔 = ∪ (𝑓 “ 𝑦))
26 id 23 . . . . . . . . . . . . . . . . 17 (𝑔 = (𝑓 ↾ 𝑦) → 𝑔 = (𝑓 ↾ 𝑦))
2719unieqd 4880 . . . . . . . . . . . . . . . . 17 (𝑔 = (𝑓 ↾ 𝑦) → ∪ dom 𝑔 = ∪ dom (𝑓 ↾ 𝑦))
2826, 27fveq12d 6884 . . . . . . . . . . . . . . . 16 (𝑔 = (𝑓 ↾ 𝑦) → (𝑔‘∪ dom 𝑔) = ((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦)))
2928fveq2d 6881 . . . . . . . . . . . . . . 15 (𝑔 = (𝑓 ↾ 𝑦) → (𝐹‘(𝑔‘∪ dom 𝑔)) = (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))
3021, 25, 29ifbieq12d 4511 . . . . . . . . . . . . . 14 (𝑔 = (𝑓 ↾ 𝑦) → if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔))) = if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦)))))
3118, 30ifbieq2d 4509 . . . . . . . . . . . . 13 (𝑔 = (𝑓 ↾ 𝑦) → if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))) = if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))))
32 eqid 2761 . . . . . . . . . . . . 13 (𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔))))) = (𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))
33 vex 3455 . . . . . . . . . . . . . 14 𝑖 ∈ V
34 imaexg 7914 . . . . . . . . . . . . . . . . 17 (𝑓 ∈ V → (𝑓 “ 𝑦) ∈ V)
3512, 34ax-mp 5 . . . . . . . . . . . . . . . 16 (𝑓 “ 𝑦) ∈ V
3635uniex 7747 . . . . . . . . . . . . . . 15 ∪ (𝑓 “ 𝑦) ∈ V
37 fvex 6890 . . . . . . . . . . . . . . 15 (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))) ∈ V
3836, 37ifex 4533 . . . . . . . . . . . . . 14 if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦)))) ∈ V
3933, 38ifex 4533 . . . . . . . . . . . . 13 if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))) ∈ V
4031, 32, 39fvmpt 6985 . . . . . . . . . . . 12 ((𝑓 ↾ 𝑦) ∈ V → ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)) = if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))))
4113, 40ax-mp 5 . . . . . . . . . . 11 ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)) = if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦)))))
42 dmres 6003 . . . . . . . . . . . . 13 dom (𝑓 ↾ 𝑦) = (𝑦 ∩ dom 𝑓)
43 onelss 6398 . . . . . . . . . . . . . . . . 17 (𝑥 ∈ On → (𝑦 ∈ 𝑥 → 𝑦 ⊆ 𝑥))
4443imp 412 . . . . . . . . . . . . . . . 16 ((𝑥 ∈ On ∧ 𝑦 ∈ 𝑥) → 𝑦 ⊆ 𝑥)
45443adant2 1149 . . . . . . . . . . . . . . 15 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → 𝑦 ⊆ 𝑥)
46 fndm 6634 . . . . . . . . . . . . . . . 16 (𝑓 Fn 𝑥 → dom 𝑓 = 𝑥)
47463ad2ant2 1152 . . . . . . . . . . . . . . 15 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → dom 𝑓 = 𝑥)
4845, 47sseqtrrd 3968 . . . . . . . . . . . . . 14 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → 𝑦 ⊆ dom 𝑓)
49 dfss2 3917 . . . . . . . . . . . . . 14 (𝑦 ⊆ dom 𝑓 ↔ (𝑦 ∩ dom 𝑓) = 𝑦)
5048, 49sylib 221 . . . . . . . . . . . . 13 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → (𝑦 ∩ dom 𝑓) = 𝑦)
5142, 50eqtrid 2808 . . . . . . . . . . . 12 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → dom (𝑓 ↾ 𝑦) = 𝑦)
52 eqeq1 2765 . . . . . . . . . . . . . 14 (dom (𝑓 ↾ 𝑦) = 𝑦 → (dom (𝑓 ↾ 𝑦) = ∅ ↔ 𝑦 = ∅))
53 limeq 6367 . . . . . . . . . . . . . . 15 (dom (𝑓 ↾ 𝑦) = 𝑦 → (Lim dom (𝑓 ↾ 𝑦) ↔ Lim 𝑦))
54 unieq 4878 . . . . . . . . . . . . . . . . 17 (dom (𝑓 ↾ 𝑦) = 𝑦 → ∪ dom (𝑓 ↾ 𝑦) = ∪ 𝑦)
5554fveq2d 6881 . . . . . . . . . . . . . . . 16 (dom (𝑓 ↾ 𝑦) = 𝑦 → ((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦)) = ((𝑓 ↾ 𝑦)‘∪ 𝑦))
5655fveq2d 6881 . . . . . . . . . . . . . . 15 (dom (𝑓 ↾ 𝑦) = 𝑦 → (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))) = (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))
5753, 56ifbieq2d 4509 . . . . . . . . . . . . . 14 (dom (𝑓 ↾ 𝑦) = 𝑦 → if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦)))) = if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦))))
5852, 57ifbieq2d 4509 . . . . . . . . . . . . 13 (dom (𝑓 ↾ 𝑦) = 𝑦 → if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))))
59 onelon 6380 . . . . . . . . . . . . . . . 16 ((𝑥 ∈ On ∧ 𝑦 ∈ 𝑥) → 𝑦 ∈ On)
60 eloni 6365 . . . . . . . . . . . . . . . 16 (𝑦 ∈ On → Ord 𝑦)
6159, 60syl 18 . . . . . . . . . . . . . . 15 ((𝑥 ∈ On ∧ 𝑦 ∈ 𝑥) → Ord 𝑦)
62613adant2 1149 . . . . . . . . . . . . . 14 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → Ord 𝑦)
63 ordzsl 7845 . . . . . . . . . . . . . . 15 (Ord 𝑦 ↔ (𝑦 = ∅ ∨ ∃𝑧 ∈ On 𝑦 = suc 𝑧 ∨ Lim 𝑦))
64 iftrue 4488 . . . . . . . . . . . . . . . . 17 (𝑦 = ∅ → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = 𝑖)
65 iftrue 4488 . . . . . . . . . . . . . . . . 17 (𝑦 = ∅ → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) = 𝑖)
6664, 65eqtr4d 2799 . . . . . . . . . . . . . . . 16 (𝑦 = ∅ → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
67 vex 3455 . . . . . . . . . . . . . . . . . . . . . . 23 𝑧 ∈ V
6867sucid 6440 . . . . . . . . . . . . . . . . . . . . . 22 𝑧 ∈ suc 𝑧
69 fvres 6896 . . . . . . . . . . . . . . . . . . . . . 22 (𝑧 ∈ suc 𝑧 → ((𝑓 ↾ suc 𝑧)‘𝑧) = (𝑓‘𝑧))
7068, 69ax-mp 5 . . . . . . . . . . . . . . . . . . . . 21 ((𝑓 ↾ suc 𝑧)‘𝑧) = (𝑓‘𝑧)
71 eloni 6365 . . . . . . . . . . . . . . . . . . . . . . 23 (𝑧 ∈ On → Ord 𝑧)
72 ordunisuc 7832 . . . . . . . . . . . . . . . . . . . . . . 23 (Ord 𝑧 → ∪ suc 𝑧 = 𝑧)
7371, 72syl 18 . . . . . . . . . . . . . . . . . . . . . 22 (𝑧 ∈ On → ∪ suc 𝑧 = 𝑧)
7473fveq2d 6881 . . . . . . . . . . . . . . . . . . . . 21 (𝑧 ∈ On → ((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧) = ((𝑓 ↾ suc 𝑧)‘𝑧))
7573fveq2d 6881 . . . . . . . . . . . . . . . . . . . . 21 (𝑧 ∈ On → (𝑓‘∪ suc 𝑧) = (𝑓‘𝑧))
7670, 74, 753eqtr4a 2822 . . . . . . . . . . . . . . . . . . . 20 (𝑧 ∈ On → ((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧) = (𝑓‘∪ suc 𝑧))
7776fveq2d 6881 . . . . . . . . . . . . . . . . . . 19 (𝑧 ∈ On → (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)) = (𝐹‘(𝑓‘∪ suc 𝑧)))
78 nsuceq0 6441 . . . . . . . . . . . . . . . . . . . . . 22 suc 𝑧 ≠ ∅
7978neii 2958 . . . . . . . . . . . . . . . . . . . . 21 ¬ suc 𝑧 = ∅
8079iffalsei 4492 . . . . . . . . . . . . . . . . . . . 20 if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))) = if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))
81 nlimsucg 7842 . . . . . . . . . . . . . . . . . . . . 21 (𝑧 ∈ V → ¬ Lim suc 𝑧)
82 iffalse 4491 . . . . . . . . . . . . . . . . . . . . 21 (¬ Lim suc 𝑧 → if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧))) = (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))
8367, 81, 82mp2b 10 . . . . . . . . . . . . . . . . . . . 20 if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧))) = (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧))
8480, 83eqtri 2784 . . . . . . . . . . . . . . . . . . 19 if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))) = (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧))
8579iffalsei 4492 . . . . . . . . . . . . . . . . . . . 20 if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧)))) = if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧)))
86 iffalse 4491 . . . . . . . . . . . . . . . . . . . . 21 (¬ Lim suc 𝑧 → if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧))) = (𝐹‘(𝑓‘∪ suc 𝑧)))
8767, 81, 86mp2b 10 . . . . . . . . . . . . . . . . . . . 20 if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧))) = (𝐹‘(𝑓‘∪ suc 𝑧))
8885, 87eqtri 2784 . . . . . . . . . . . . . . . . . . 19 if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧)))) = (𝐹‘(𝑓‘∪ suc 𝑧))
8977, 84, 883eqtr4g 2821 . . . . . . . . . . . . . . . . . 18 (𝑧 ∈ On → if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))) = if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧)))))
90 eqeq1 2765 . . . . . . . . . . . . . . . . . . . 20 (𝑦 = suc 𝑧 → (𝑦 = ∅ ↔ suc 𝑧 = ∅))
91 limeq 6367 . . . . . . . . . . . . . . . . . . . . 21 (𝑦 = suc 𝑧 → (Lim 𝑦 ↔ Lim suc 𝑧))
92 reseq2 5965 . . . . . . . . . . . . . . . . . . . . . . 23 (𝑦 = suc 𝑧 → (𝑓 ↾ 𝑦) = (𝑓 ↾ suc 𝑧))
93 unieq 4878 . . . . . . . . . . . . . . . . . . . . . . 23 (𝑦 = suc 𝑧 → ∪ 𝑦 = ∪ suc 𝑧)
9492, 93fveq12d 6884 . . . . . . . . . . . . . . . . . . . . . 22 (𝑦 = suc 𝑧 → ((𝑓 ↾ 𝑦)‘∪ 𝑦) = ((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧))
9594fveq2d 6881 . . . . . . . . . . . . . . . . . . . . 21 (𝑦 = suc 𝑧 → (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)) = (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))
9691, 95ifbieq2d 4509 . . . . . . . . . . . . . . . . . . . 20 (𝑦 = suc 𝑧 → if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦))) = if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧))))
9790, 96ifbieq2d 4509 . . . . . . . . . . . . . . . . . . 19 (𝑦 = suc 𝑧 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))))
9893fveq2d 6881 . . . . . . . . . . . . . . . . . . . . . 22 (𝑦 = suc 𝑧 → (𝑓‘∪ 𝑦) = (𝑓‘∪ suc 𝑧))
9998fveq2d 6881 . . . . . . . . . . . . . . . . . . . . 21 (𝑦 = suc 𝑧 → (𝐹‘(𝑓‘∪ 𝑦)) = (𝐹‘(𝑓‘∪ suc 𝑧)))
10091, 99ifbieq2d 4509 . . . . . . . . . . . . . . . . . . . 20 (𝑦 = suc 𝑧 → if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))) = if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧))))
10190, 100ifbieq2d 4509 . . . . . . . . . . . . . . . . . . 19 (𝑦 = suc 𝑧 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) = if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧)))))
10297, 101eqeq12d 2777 . . . . . . . . . . . . . . . . . 18 (𝑦 = suc 𝑧 → (if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) ↔ if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ suc 𝑧)‘∪ suc 𝑧)))) = if(suc 𝑧 = ∅, 𝑖, if(Lim suc 𝑧, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ suc 𝑧))))))
10389, 102syl5ibrcom 250 . . . . . . . . . . . . . . . . 17 (𝑧 ∈ On → (𝑦 = suc 𝑧 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
104103rexlimiv 3157 . . . . . . . . . . . . . . . 16 (∃𝑧 ∈ On 𝑦 = suc 𝑧 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
105 iftrue 4488 . . . . . . . . . . . . . . . . . 18 (Lim 𝑦 → if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦))) = ∪ (𝑓 “ 𝑦))
106 df-lim 6360 . . . . . . . . . . . . . . . . . . . . 21 (Lim 𝑦 ↔ (Ord 𝑦 ∧ 𝑦 ≠ ∅ ∧ 𝑦 = ∪ 𝑦))
107106simp2bi 1164 . . . . . . . . . . . . . . . . . . . 20 (Lim 𝑦 → 𝑦 ≠ ∅)
108107neneqd 2961 . . . . . . . . . . . . . . . . . . 19 (Lim 𝑦 → ¬ 𝑦 = ∅)
109108iffalsed 4493 . . . . . . . . . . . . . . . . . 18 (Lim 𝑦 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦))))
110 iftrue 4488 . . . . . . . . . . . . . . . . . 18 (Lim 𝑦 → if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))) = ∪ (𝑓 “ 𝑦))
111105, 109, 1103eqtr4d 2806 . . . . . . . . . . . . . . . . 17 (Lim 𝑦 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))
112108iffalsed 4493 . . . . . . . . . . . . . . . . 17 (Lim 𝑦 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))) = if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))
113111, 112eqtr4d 2799 . . . . . . . . . . . . . . . 16 (Lim 𝑦 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
11466, 104, 1133jaoi 1454 . . . . . . . . . . . . . . 15 ((𝑦 = ∅ ∨ ∃𝑧 ∈ On 𝑦 = suc 𝑧 ∨ Lim 𝑦) → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
11563, 114sylbi 220 . . . . . . . . . . . . . 14 (Ord 𝑦 → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
11662, 115syl 18 . . . . . . . . . . . . 13 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ 𝑦)))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
11758, 116sylan9eqr 2818 . . . . . . . . . . . 12 (((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) ∧ dom (𝑓 ↾ 𝑦) = 𝑦) → if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
11851, 117mpdan 700 . . . . . . . . . . 11 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → if(dom (𝑓 ↾ 𝑦) = ∅, 𝑖, if(Lim dom (𝑓 ↾ 𝑦), ∪ (𝑓 “ 𝑦), (𝐹‘((𝑓 ↾ 𝑦)‘∪ dom (𝑓 ↾ 𝑦))))) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
11941, 118eqtrid 2808 . . . . . . . . . 10 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))
120119eqeq2d 2772 . . . . . . . . 9 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥 ∧ 𝑦 ∈ 𝑥) → ((𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)) ↔ (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
1211203expa 1136 . . . . . . . 8 (((𝑥 ∈ On ∧ 𝑓 Fn 𝑥) ∧ 𝑦 ∈ 𝑥) → ((𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)) ↔ (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
122121ralbidva 3184 . . . . . . 7 ((𝑥 ∈ On ∧ 𝑓 Fn 𝑥) → (∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)) ↔ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
123122pm5.32da 590 . . . . . 6 (𝑥 ∈ On → ((𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦))) ↔ (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))))
124123rexbiia 3108 . . . . 5 (∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦))) ↔ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦))))))
125124abbii 2828 . . . 4 {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)))} = {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))}
126125unieqi 4879 . . 3 ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = ((𝑔 ∈ V ↦ if(𝑔 = ∅, 𝑖, if(Lim dom 𝑔, ∪ ran 𝑔, (𝐹‘(𝑔‘∪ dom 𝑔)))))‘(𝑓 ↾ 𝑦)))} = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))}
12710, 11, 1263eqtri 2788 . 2 rec(𝐹, 𝑖) = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝑖, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))}
1289, 127vtoclg 3518 1 (𝐼 ∈ 𝑉 → rec(𝐹, 𝐼) = ∪ {𝑓 ∣ ∃𝑥 ∈ On (𝑓 Fn 𝑥 ∧ ∀𝑦 ∈ 𝑥 (𝑓‘𝑦) = if(𝑦 = ∅, 𝐼, if(Lim 𝑦, ∪ (𝑓 “ 𝑦), (𝐹‘(𝑓‘∪ 𝑦)))))})
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  ¬ wn 3   → wi 4   ↔ wb 209   ∧ wa 401   ∨ w3o 1102   ∧ w3a 1103   = wceq 1570   ∈ wcel 2145  {cab 2739   ≠ wne 2956  ∀wral 3077  ∃wrex 3087  Vcvv 3451   ∩ cin 3898   ⊆ wss 3899  ∅c0 4279  ifcif 4482  ∪ cuni 4867   ↦ cmpt 5186  dom cdm 5651  ran crn 5652   ↾ cres 5653   “ cima 5654  Rel wrel 5656  Ord word 6354  Oncon0 6355  Lim wlim 6356  suc csuc 6357   Fn wfn 6526  ‘cfv 6531  recscrecs 8362  reccrdg 8401
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2147  ax-9 2155  ax-10 2178  ax-11 2194  ax-12 2213  ax-ext 2733  ax-sep 5249  ax-nul 5260  ax-pr 5391  ax-un 7740
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1813  df-nf 1817  df-sb 2100  df-mo 2565  df-eu 2595  df-clab 2740  df-cleq 2753  df-clel 2836  df-nfc 2910  df-ne 2957  df-ral 3078  df-rex 3088  df-rab 3414  df-v 3453  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-pss 3919  df-nul 4280  df-if 4483  df-pw 4559  df-sn 4585  df-pr 4587  df-op 4591  df-uni 4868  df-br 5104  df-opab 5168  df-mpt 5187  df-tr 5213  df-id 5546  df-eprel 5551  df-po 5559  df-so 5560  df-fr 5604  df-we 5606  df-xp 5657  df-rel 5658  df-cnv 5659  df-co 5660  df-dm 5661  df-rn 5662  df-res 5663  df-ima 5664  df-pred 6297  df-ord 6358  df-on 6359  df-lim 6360  df-suc 6361  df-iota 6487  df-fun 6533  df-fn 6534  df-f 6535  df-fo 6537  df-fv 6539  df-ov 7415  df-2nd 7991  df-frecs 8283  df-wrecs 8314  df-recs 8363  df-rdg 8402
This theorem is used by:  dfrdg3  36528
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