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Theorem sbiota1 41125
 Description: Theorem *14.25 in [WhiteheadRussell] p. 192. (Contributed by Andrew Salmon, 12-Jul-2011.)
Assertion
Ref Expression
sbiota1 (∃!𝑥𝜑 → (∀𝑥(𝜑𝜓) ↔ [(℩𝑥𝜑) / 𝑥]𝜓))

Proof of Theorem sbiota1
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 eu6 2637 . . . 4 (∃!𝑥𝜑 ↔ ∃𝑦𝑥(𝜑𝑥 = 𝑦))
21biimpi 219 . . 3 (∃!𝑥𝜑 → ∃𝑦𝑥(𝜑𝑥 = 𝑦))
3 iota4 6309 . . 3 (∃!𝑥𝜑[(℩𝑥𝜑) / 𝑥]𝜑)
4 iotaval 6302 . . . . . 6 (∀𝑥(𝜑𝑥 = 𝑦) → (℩𝑥𝜑) = 𝑦)
54eqcomd 2807 . . . . 5 (∀𝑥(𝜑𝑥 = 𝑦) → 𝑦 = (℩𝑥𝜑))
6 spsbim 2077 . . . . . . . 8 (∀𝑥(𝜑𝜓) → ([𝑦 / 𝑥]𝜑 → [𝑦 / 𝑥]𝜓))
7 sbsbc 3727 . . . . . . . 8 ([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜑)
8 sbsbc 3727 . . . . . . . 8 ([𝑦 / 𝑥]𝜓[𝑦 / 𝑥]𝜓)
96, 7, 83imtr3g 298 . . . . . . 7 (∀𝑥(𝜑𝜓) → ([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜓))
10 dfsbcq 3725 . . . . . . . 8 (𝑦 = (℩𝑥𝜑) → ([𝑦 / 𝑥]𝜑[(℩𝑥𝜑) / 𝑥]𝜑))
11 dfsbcq 3725 . . . . . . . 8 (𝑦 = (℩𝑥𝜑) → ([𝑦 / 𝑥]𝜓[(℩𝑥𝜑) / 𝑥]𝜓))
1210, 11imbi12d 348 . . . . . . 7 (𝑦 = (℩𝑥𝜑) → (([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜓) ↔ ([(℩𝑥𝜑) / 𝑥]𝜑[(℩𝑥𝜑) / 𝑥]𝜓)))
139, 12syl5ib 247 . . . . . 6 (𝑦 = (℩𝑥𝜑) → (∀𝑥(𝜑𝜓) → ([(℩𝑥𝜑) / 𝑥]𝜑[(℩𝑥𝜑) / 𝑥]𝜓)))
1413com23 86 . . . . 5 (𝑦 = (℩𝑥𝜑) → ([(℩𝑥𝜑) / 𝑥]𝜑 → (∀𝑥(𝜑𝜓) → [(℩𝑥𝜑) / 𝑥]𝜓)))
155, 14syl 17 . . . 4 (∀𝑥(𝜑𝑥 = 𝑦) → ([(℩𝑥𝜑) / 𝑥]𝜑 → (∀𝑥(𝜑𝜓) → [(℩𝑥𝜑) / 𝑥]𝜓)))
1615exlimiv 1931 . . 3 (∃𝑦𝑥(𝜑𝑥 = 𝑦) → ([(℩𝑥𝜑) / 𝑥]𝜑 → (∀𝑥(𝜑𝜓) → [(℩𝑥𝜑) / 𝑥]𝜓)))
172, 3, 16sylc 65 . 2 (∃!𝑥𝜑 → (∀𝑥(𝜑𝜓) → [(℩𝑥𝜑) / 𝑥]𝜓))
18 iotaexeu 41109 . . . . 5 (∃!𝑥𝜑 → (℩𝑥𝜑) ∈ V)
1910, 11anbi12d 633 . . . . . . . 8 (𝑦 = (℩𝑥𝜑) → (([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜓) ↔ ([(℩𝑥𝜑) / 𝑥]𝜑[(℩𝑥𝜑) / 𝑥]𝜓)))
2019imbi1d 345 . . . . . . 7 (𝑦 = (℩𝑥𝜑) → ((([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜓) → ∃𝑥(𝜑𝜓)) ↔ (([(℩𝑥𝜑) / 𝑥]𝜑[(℩𝑥𝜑) / 𝑥]𝜓) → ∃𝑥(𝜑𝜓))))
21 sbcan 3771 . . . . . . . 8 ([𝑦 / 𝑥](𝜑𝜓) ↔ ([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜓))
22 spesbc 3814 . . . . . . . 8 ([𝑦 / 𝑥](𝜑𝜓) → ∃𝑥(𝜑𝜓))
2321, 22sylbir 238 . . . . . . 7 (([𝑦 / 𝑥]𝜑[𝑦 / 𝑥]𝜓) → ∃𝑥(𝜑𝜓))
2420, 23vtoclg 3518 . . . . . 6 ((℩𝑥𝜑) ∈ V → (([(℩𝑥𝜑) / 𝑥]𝜑[(℩𝑥𝜑) / 𝑥]𝜓) → ∃𝑥(𝜑𝜓)))
2524expd 419 . . . . 5 ((℩𝑥𝜑) ∈ V → ([(℩𝑥𝜑) / 𝑥]𝜑 → ([(℩𝑥𝜑) / 𝑥]𝜓 → ∃𝑥(𝜑𝜓))))
2618, 3, 25sylc 65 . . . 4 (∃!𝑥𝜑 → ([(℩𝑥𝜑) / 𝑥]𝜓 → ∃𝑥(𝜑𝜓)))
2726anc2li 559 . . 3 (∃!𝑥𝜑 → ([(℩𝑥𝜑) / 𝑥]𝜓 → (∃!𝑥𝜑 ∧ ∃𝑥(𝜑𝜓))))
28 eupicka 2699 . . 3 ((∃!𝑥𝜑 ∧ ∃𝑥(𝜑𝜓)) → ∀𝑥(𝜑𝜓))
2927, 28syl6 35 . 2 (∃!𝑥𝜑 → ([(℩𝑥𝜑) / 𝑥]𝜓 → ∀𝑥(𝜑𝜓)))
3017, 29impbid 215 1 (∃!𝑥𝜑 → (∀𝑥(𝜑𝜓) ↔ [(℩𝑥𝜑) / 𝑥]𝜓))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 209   ∧ wa 399  ∀wal 1536   = wceq 1538  ∃wex 1781  [wsb 2069   ∈ wcel 2112  ∃!weu 2631  Vcvv 3444  [wsbc 3723  ℩cio 6285 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2114  ax-9 2122  ax-10 2143  ax-11 2159  ax-12 2176  ax-ext 2773 This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2070  df-mo 2601  df-eu 2632  df-clab 2780  df-cleq 2794  df-clel 2873  df-nfc 2941  df-ral 3114  df-rex 3115  df-v 3446  df-sbc 3724  df-un 3889  df-in 3891  df-ss 3901  df-sn 4529  df-pr 4531  df-uni 4804  df-iota 6287 This theorem is referenced by:  sbaniota  41126
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