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Theorem aiotaexb 43503
 Description: The alternate iota over a wff 𝜑 is a set iff there is a unique value 𝑥 satisfying 𝜑. (Contributed by AV, 25-Aug-2022.)
Assertion
Ref Expression
aiotaexb (∃!𝑥𝜑 ↔ (℩'𝑥𝜑) ∈ V)

Proof of Theorem aiotaexb
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 intexab 5225 . 2 (∃𝑦{𝑥𝜑} = {𝑦} ↔ {𝑦 ∣ {𝑥𝜑} = {𝑦}} ∈ V)
2 euabsn2 4644 . 2 (∃!𝑥𝜑 ↔ ∃𝑦{𝑥𝜑} = {𝑦})
3 df-aiota 43499 . . 3 (℩'𝑥𝜑) = {𝑦 ∣ {𝑥𝜑} = {𝑦}}
43eleq1i 2906 . 2 ((℩'𝑥𝜑) ∈ V ↔ {𝑦 ∣ {𝑥𝜑} = {𝑦}} ∈ V)
51, 2, 43bitr4i 306 1 (∃!𝑥𝜑 ↔ (℩'𝑥𝜑) ∈ V)
 Colors of variables: wff setvar class Syntax hints:   ↔ wb 209   = wceq 1538  ∃wex 1781   ∈ wcel 2115  ∃!weu 2654  {cab 2802  Vcvv 3479  {csn 4548  ∩ cint 4859  ℩'caiota 43497 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 1912  ax-6 1971  ax-7 2016  ax-8 2117  ax-9 2125  ax-10 2146  ax-11 2162  ax-12 2179  ax-ext 2796  ax-sep 5186 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 2071  df-mo 2624  df-eu 2655  df-clab 2803  df-cleq 2817  df-clel 2896  df-nfc 2964  df-ne 3014  df-ral 3137  df-rab 3141  df-v 3481  df-dif 3921  df-in 3925  df-ss 3935  df-nul 4275  df-sn 4549  df-int 4860  df-aiota 43499 This theorem is referenced by:  aiotavb  43504  iotan0aiotaex  43505  aiotaexaiotaiota  43506  aiota0ndef  43509
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