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Theorem ndmfvg 5204
 Description: The value of a class outside its domain is the empty set. (Contributed by Jim Kingdon, 15-Jan-2019.)
Assertion
Ref Expression
ndmfvg ((𝐴 ∈ V ∧ ¬ 𝐴 ∈ dom 𝐹) → (𝐹𝐴) = ∅)

Proof of Theorem ndmfvg
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 euex 1930 . . . . 5 (∃!𝑥 𝐴𝐹𝑥 → ∃𝑥 𝐴𝐹𝑥)
2 eldmg 4530 . . . . 5 (𝐴 ∈ V → (𝐴 ∈ dom 𝐹 ↔ ∃𝑥 𝐴𝐹𝑥))
31, 2syl5ibr 145 . . . 4 (𝐴 ∈ V → (∃!𝑥 𝐴𝐹𝑥𝐴 ∈ dom 𝐹))
43con3d 561 . . 3 (𝐴 ∈ V → (¬ 𝐴 ∈ dom 𝐹 → ¬ ∃!𝑥 𝐴𝐹𝑥))
5 tz6.12-2 5169 . . 3 (¬ ∃!𝑥 𝐴𝐹𝑥 → (𝐹𝐴) = ∅)
64, 5syl6 29 . 2 (𝐴 ∈ V → (¬ 𝐴 ∈ dom 𝐹 → (𝐹𝐴) = ∅))
76imp 115 1 ((𝐴 ∈ V ∧ ¬ 𝐴 ∈ dom 𝐹) → (𝐹𝐴) = ∅)
 Colors of variables: wff set class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 97   = wceq 1243  ∃wex 1381   ∈ wcel 1393  ∃!weu 1900  Vcvv 2557  ∅c0 3224   class class class wbr 3764  dom cdm 4345  ‘cfv 4902 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-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022 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-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-ral 2311  df-rex 2312  df-v 2559  df-dif 2920  df-un 2922  df-in 2924  df-ss 2931  df-nul 3225  df-sn 3381  df-pr 3382  df-op 3384  df-uni 3581  df-br 3765  df-dm 4355  df-iota 4867  df-fv 4910 This theorem is referenced by:  ovprc  5540
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