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Theorem tfri2 5939
Description: Principle of Transfinite Recursion, part 2 of 3. Theorem 7.41(2) of [TakeutiZaring] p. 47, with an additional condition on the recursion rule 𝐺 ( as described at tfri1 5938). Here we show that the function 𝐹 has the property that for any function 𝐺 satisfying that condition, the "next" value of 𝐹 is 𝐺 recursively applied to all "previous" values of 𝐹. (Contributed by Jim Kingdon, 4-May-2019.)
Hypotheses
Ref Expression
tfri1.1 𝐹 = recs(𝐺)
tfri1.2 (Fun 𝐺 ∧ (𝐺𝑥) ∈ V)
Assertion
Ref Expression
tfri2 (𝐴 ∈ On → (𝐹𝐴) = (𝐺‘(𝐹𝐴)))
Distinct variable group:   𝑥,𝐺
Allowed substitution hints:   𝐴(𝑥)   𝐹(𝑥)

Proof of Theorem tfri2
StepHypRef Expression
1 tfri1.1 . . . . 5 𝐹 = recs(𝐺)
2 tfri1.2 . . . . 5 (Fun 𝐺 ∧ (𝐺𝑥) ∈ V)
31, 2tfri1 5938 . . . 4 𝐹 Fn On
4 fndm 4985 . . . 4 (𝐹 Fn On → dom 𝐹 = On)
53, 4ax-mp 7 . . 3 dom 𝐹 = On
65eleq2i 2104 . 2 (𝐴 ∈ dom 𝐹𝐴 ∈ On)
71tfr2a 5923 . 2 (𝐴 ∈ dom 𝐹 → (𝐹𝐴) = (𝐺‘(𝐹𝐴)))
86, 7sylbir 125 1 (𝐴 ∈ On → (𝐹𝐴) = (𝐺‘(𝐹𝐴)))
Colors of variables: wff set class
Syntax hints:  wi 4  wa 97   = wceq 1243  wcel 1393  Vcvv 2554  Oncon0 4096  dom cdm 4332  cres 4334  Fun wfun 4883   Fn wfn 4884  cfv 4889  recscrecs 5906
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-13 1404  ax-14 1405  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022  ax-coll 3869  ax-sep 3872  ax-pow 3924  ax-pr 3941  ax-un 4166  ax-setind 4256
This theorem depends on definitions:  df-bi 110  df-3an 887  df-tru 1246  df-fal 1249  df-nf 1350  df-sb 1646  df-eu 1903  df-mo 1904  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ne 2206  df-ral 2308  df-rex 2309  df-reu 2310  df-rab 2312  df-v 2556  df-sbc 2762  df-csb 2850  df-dif 2917  df-un 2919  df-in 2921  df-ss 2928  df-nul 3222  df-pw 3358  df-sn 3378  df-pr 3379  df-op 3381  df-uni 3578  df-iun 3656  df-br 3762  df-opab 3816  df-mpt 3817  df-tr 3852  df-id 4027  df-iord 4099  df-on 4101  df-suc 4104  df-xp 4338  df-rel 4339  df-cnv 4340  df-co 4341  df-dm 4342  df-rn 4343  df-res 4344  df-ima 4345  df-iota 4854  df-fun 4891  df-fn 4892  df-f 4893  df-f1 4894  df-fo 4895  df-f1o 4896  df-fv 4897  df-recs 5907
This theorem is referenced by:  tfri3  5940
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