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Theorem dfac3 9143
 Description: Equivalence of two versions of the Axiom of Choice. The left-hand side is defined as the Axiom of Choice (first form) of [Enderton] p. 49. The right-hand side is the Axiom of Choice of [TakeutiZaring] p. 83. The proof does not depend on AC. (Contributed by NM, 24-Mar-2004.) (Revised by Stefan O'Rear, 22-Feb-2015.)
Assertion
Ref Expression
dfac3 (CHOICE ↔ ∀𝑥𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
Distinct variable group:   𝑥,𝑓,𝑧

Proof of Theorem dfac3
Dummy variables 𝑦 𝑤 𝑣 𝑢 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 df-ac 9138 . 2 (CHOICE ↔ ∀𝑦𝑓(𝑓𝑦𝑓 Fn dom 𝑦))
2 vex 3352 . . . . . . . 8 𝑥 ∈ V
3 vuniex 7100 . . . . . . . 8 𝑥 ∈ V
42, 3xpex 7108 . . . . . . 7 (𝑥 × 𝑥) ∈ V
5 simpl 468 . . . . . . . . . 10 ((𝑤𝑥𝑣𝑤) → 𝑤𝑥)
6 elunii 4577 . . . . . . . . . . 11 ((𝑣𝑤𝑤𝑥) → 𝑣 𝑥)
76ancoms 455 . . . . . . . . . 10 ((𝑤𝑥𝑣𝑤) → 𝑣 𝑥)
85, 7jca 495 . . . . . . . . 9 ((𝑤𝑥𝑣𝑤) → (𝑤𝑥𝑣 𝑥))
98ssopab2i 5136 . . . . . . . 8 {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣 𝑥)}
10 df-xp 5255 . . . . . . . 8 (𝑥 × 𝑥) = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣 𝑥)}
119, 10sseqtr4i 3785 . . . . . . 7 {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ⊆ (𝑥 × 𝑥)
124, 11ssexi 4934 . . . . . 6 {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∈ V
13 sseq2 3774 . . . . . . . 8 (𝑦 = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → (𝑓𝑦𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}))
14 dmeq 5462 . . . . . . . . 9 (𝑦 = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → dom 𝑦 = dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)})
1514fneq2d 6122 . . . . . . . 8 (𝑦 = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → (𝑓 Fn dom 𝑦𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}))
1613, 15anbi12d 608 . . . . . . 7 (𝑦 = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → ((𝑓𝑦𝑓 Fn dom 𝑦) ↔ (𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)})))
1716exbidv 2001 . . . . . 6 (𝑦 = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → (∃𝑓(𝑓𝑦𝑓 Fn dom 𝑦) ↔ ∃𝑓(𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)})))
1812, 17spcv 3448 . . . . 5 (∀𝑦𝑓(𝑓𝑦𝑓 Fn dom 𝑦) → ∃𝑓(𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}))
19 fndm 6130 . . . . . . . . . . . . 13 (𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → dom 𝑓 = dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)})
20 eleq2 2838 . . . . . . . . . . . . . 14 (dom 𝑓 = dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → (𝑧 ∈ dom 𝑓𝑧 ∈ dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}))
21 dmopab 5473 . . . . . . . . . . . . . . . 16 dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} = {𝑤 ∣ ∃𝑣(𝑤𝑥𝑣𝑤)}
2221eleq2i 2841 . . . . . . . . . . . . . . 15 (𝑧 ∈ dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ↔ 𝑧 ∈ {𝑤 ∣ ∃𝑣(𝑤𝑥𝑣𝑤)})
23 vex 3352 . . . . . . . . . . . . . . . 16 𝑧 ∈ V
24 elequ1 2151 . . . . . . . . . . . . . . . . . 18 (𝑤 = 𝑧 → (𝑤𝑥𝑧𝑥))
25 eleq2 2838 . . . . . . . . . . . . . . . . . 18 (𝑤 = 𝑧 → (𝑣𝑤𝑣𝑧))
2624, 25anbi12d 608 . . . . . . . . . . . . . . . . 17 (𝑤 = 𝑧 → ((𝑤𝑥𝑣𝑤) ↔ (𝑧𝑥𝑣𝑧)))
2726exbidv 2001 . . . . . . . . . . . . . . . 16 (𝑤 = 𝑧 → (∃𝑣(𝑤𝑥𝑣𝑤) ↔ ∃𝑣(𝑧𝑥𝑣𝑧)))
2823, 27elab 3499 . . . . . . . . . . . . . . 15 (𝑧 ∈ {𝑤 ∣ ∃𝑣(𝑤𝑥𝑣𝑤)} ↔ ∃𝑣(𝑧𝑥𝑣𝑧))
29 19.42v 2032 . . . . . . . . . . . . . . . 16 (∃𝑣(𝑧𝑥𝑣𝑧) ↔ (𝑧𝑥 ∧ ∃𝑣 𝑣𝑧))
30 n0 4076 . . . . . . . . . . . . . . . . 17 (𝑧 ≠ ∅ ↔ ∃𝑣 𝑣𝑧)
3130anbi2i 601 . . . . . . . . . . . . . . . 16 ((𝑧𝑥𝑧 ≠ ∅) ↔ (𝑧𝑥 ∧ ∃𝑣 𝑣𝑧))
3229, 31bitr4i 267 . . . . . . . . . . . . . . 15 (∃𝑣(𝑧𝑥𝑣𝑧) ↔ (𝑧𝑥𝑧 ≠ ∅))
3322, 28, 323bitrri 287 . . . . . . . . . . . . . 14 ((𝑧𝑥𝑧 ≠ ∅) ↔ 𝑧 ∈ dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)})
3420, 33syl6rbbr 279 . . . . . . . . . . . . 13 (dom 𝑓 = dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → ((𝑧𝑥𝑧 ≠ ∅) ↔ 𝑧 ∈ dom 𝑓))
3519, 34syl 17 . . . . . . . . . . . 12 (𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → ((𝑧𝑥𝑧 ≠ ∅) ↔ 𝑧 ∈ dom 𝑓))
3635adantl 467 . . . . . . . . . . 11 ((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → ((𝑧𝑥𝑧 ≠ ∅) ↔ 𝑧 ∈ dom 𝑓))
37 fnfun 6128 . . . . . . . . . . . 12 (𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} → Fun 𝑓)
38 funfvima3 6637 . . . . . . . . . . . . 13 ((Fun 𝑓𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → (𝑧 ∈ dom 𝑓 → (𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧})))
3938ancoms 455 . . . . . . . . . . . 12 ((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ Fun 𝑓) → (𝑧 ∈ dom 𝑓 → (𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧})))
4037, 39sylan2 572 . . . . . . . . . . 11 ((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → (𝑧 ∈ dom 𝑓 → (𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧})))
4136, 40sylbid 230 . . . . . . . . . 10 ((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → ((𝑧𝑥𝑧 ≠ ∅) → (𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧})))
4241imp 393 . . . . . . . . 9 (((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) ∧ (𝑧𝑥𝑧 ≠ ∅)) → (𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}))
43 ibar 512 . . . . . . . . . . . . 13 (𝑧𝑥 → (𝑢𝑧 ↔ (𝑧𝑥𝑢𝑧)))
4443abbi2dv 2890 . . . . . . . . . . . 12 (𝑧𝑥𝑧 = {𝑢 ∣ (𝑧𝑥𝑢𝑧)})
45 imasng 5628 . . . . . . . . . . . . . 14 (𝑧 ∈ V → ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}) = {𝑢𝑧{⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}𝑢})
4623, 45ax-mp 5 . . . . . . . . . . . . 13 ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}) = {𝑢𝑧{⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}𝑢}
47 vex 3352 . . . . . . . . . . . . . . 15 𝑢 ∈ V
48 elequ1 2151 . . . . . . . . . . . . . . . 16 (𝑣 = 𝑢 → (𝑣𝑧𝑢𝑧))
4948anbi2d 606 . . . . . . . . . . . . . . 15 (𝑣 = 𝑢 → ((𝑧𝑥𝑣𝑧) ↔ (𝑧𝑥𝑢𝑧)))
50 eqid 2770 . . . . . . . . . . . . . . 15 {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} = {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}
5123, 47, 26, 49, 50brab 5131 . . . . . . . . . . . . . 14 (𝑧{⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}𝑢 ↔ (𝑧𝑥𝑢𝑧))
5251abbii 2887 . . . . . . . . . . . . 13 {𝑢𝑧{⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}𝑢} = {𝑢 ∣ (𝑧𝑥𝑢𝑧)}
5346, 52eqtri 2792 . . . . . . . . . . . 12 ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}) = {𝑢 ∣ (𝑧𝑥𝑢𝑧)}
5444, 53syl6reqr 2823 . . . . . . . . . . 11 (𝑧𝑥 → ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}) = 𝑧)
5554eleq2d 2835 . . . . . . . . . 10 (𝑧𝑥 → ((𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}) ↔ (𝑓𝑧) ∈ 𝑧))
5655ad2antrl 699 . . . . . . . . 9 (((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) ∧ (𝑧𝑥𝑧 ≠ ∅)) → ((𝑓𝑧) ∈ ({⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} “ {𝑧}) ↔ (𝑓𝑧) ∈ 𝑧))
5742, 56mpbid 222 . . . . . . . 8 (((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) ∧ (𝑧𝑥𝑧 ≠ ∅)) → (𝑓𝑧) ∈ 𝑧)
5857exp32 407 . . . . . . 7 ((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → (𝑧𝑥 → (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧)))
5958ralrimiv 3113 . . . . . 6 ((𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → ∀𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
6059eximi 1909 . . . . 5 (∃𝑓(𝑓 ⊆ {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)} ∧ 𝑓 Fn dom {⟨𝑤, 𝑣⟩ ∣ (𝑤𝑥𝑣𝑤)}) → ∃𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
6118, 60syl 17 . . . 4 (∀𝑦𝑓(𝑓𝑦𝑓 Fn dom 𝑦) → ∃𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
6261alrimiv 2006 . . 3 (∀𝑦𝑓(𝑓𝑦𝑓 Fn dom 𝑦) → ∀𝑥𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
63 eqid 2770 . . . . 5 (𝑤 ∈ dom 𝑦 ↦ (𝑓‘{𝑢𝑤𝑦𝑢})) = (𝑤 ∈ dom 𝑦 ↦ (𝑓‘{𝑢𝑤𝑦𝑢}))
6463aceq3lem 9142 . . . 4 (∀𝑥𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧) → ∃𝑓(𝑓𝑦𝑓 Fn dom 𝑦))
6564alrimiv 2006 . . 3 (∀𝑥𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧) → ∀𝑦𝑓(𝑓𝑦𝑓 Fn dom 𝑦))
6662, 65impbii 199 . 2 (∀𝑦𝑓(𝑓𝑦𝑓 Fn dom 𝑦) ↔ ∀𝑥𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
671, 66bitri 264 1 (CHOICE ↔ ∀𝑥𝑓𝑧𝑥 (𝑧 ≠ ∅ → (𝑓𝑧) ∈ 𝑧))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 196   ∧ wa 382  ∀wal 1628   = wceq 1630  ∃wex 1851   ∈ wcel 2144  {cab 2756   ≠ wne 2942  ∀wral 3060  Vcvv 3349   ⊆ wss 3721  ∅c0 4061  {csn 4314  ∪ cuni 4572   class class class wbr 4784  {copab 4844   ↦ cmpt 4861   × cxp 5247  dom cdm 5249   “ cima 5252  Fun wfun 6025   Fn wfn 6026  ‘cfv 6031  CHOICEwac 9137 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1869  ax-4 1884  ax-5 1990  ax-6 2056  ax-7 2092  ax-8 2146  ax-9 2153  ax-10 2173  ax-11 2189  ax-12 2202  ax-13 2407  ax-ext 2750  ax-sep 4912  ax-nul 4920  ax-pow 4971  ax-pr 5034  ax-un 7095 This theorem depends on definitions:  df-bi 197  df-an 383  df-or 827  df-3an 1072  df-tru 1633  df-ex 1852  df-nf 1857  df-sb 2049  df-eu 2621  df-mo 2622  df-clab 2757  df-cleq 2763  df-clel 2766  df-nfc 2901  df-ne 2943  df-ral 3065  df-rex 3066  df-rab 3069  df-v 3351  df-sbc 3586  df-dif 3724  df-un 3726  df-in 3728  df-ss 3735  df-nul 4062  df-if 4224  df-pw 4297  df-sn 4315  df-pr 4317  df-op 4321  df-uni 4573  df-br 4785  df-opab 4845  df-mpt 4862  df-id 5157  df-xp 5255  df-rel 5256  df-cnv 5257  df-co 5258  df-dm 5259  df-rn 5260  df-res 5261  df-ima 5262  df-iota 5994  df-fun 6033  df-fn 6034  df-fv 6039  df-ac 9138 This theorem is referenced by:  dfac4  9144  dfac5  9150  dfac2a  9151  dfac2b  9152  dfac2OLD  9154  dfac8  9158  dfac9  9159  ac4  9498  dfac11  38151
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