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Theorem 1stexg 6065
Description: Existence of the first member of a set. (Contributed by Jim Kingdon, 26-Jan-2019.)
Assertion
Ref Expression
1stexg (𝐴𝑉 → (1st𝐴) ∈ V)

Proof of Theorem 1stexg
StepHypRef Expression
1 elex 2697 . 2 (𝐴𝑉𝐴 ∈ V)
2 fo1st 6055 . . . 4 1st :V–onto→V
3 fofn 5347 . . . 4 (1st :V–onto→V → 1st Fn V)
42, 3ax-mp 5 . . 3 1st Fn V
5 funfvex 5438 . . . 4 ((Fun 1st𝐴 ∈ dom 1st ) → (1st𝐴) ∈ V)
65funfni 5223 . . 3 ((1st Fn V ∧ 𝐴 ∈ V) → (1st𝐴) ∈ V)
74, 6mpan 420 . 2 (𝐴 ∈ V → (1st𝐴) ∈ V)
81, 7syl 14 1 (𝐴𝑉 → (1st𝐴) ∈ V)
Colors of variables: wff set class
Syntax hints:  wi 4  wcel 1480  Vcvv 2686   Fn wfn 5118  ontowfo 5121  cfv 5123  1st c1st 6036
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 698  ax-5 1423  ax-7 1424  ax-gen 1425  ax-ie1 1469  ax-ie2 1470  ax-8 1482  ax-10 1483  ax-11 1484  ax-i12 1485  ax-bndl 1486  ax-4 1487  ax-13 1491  ax-14 1492  ax-17 1506  ax-i9 1510  ax-ial 1514  ax-i5r 1515  ax-ext 2121  ax-sep 4046  ax-pow 4098  ax-pr 4131  ax-un 4355
This theorem depends on definitions:  df-bi 116  df-3an 964  df-tru 1334  df-nf 1437  df-sb 1736  df-eu 2002  df-mo 2003  df-clab 2126  df-cleq 2132  df-clel 2135  df-nfc 2270  df-ral 2421  df-rex 2422  df-v 2688  df-sbc 2910  df-un 3075  df-in 3077  df-ss 3084  df-pw 3512  df-sn 3533  df-pr 3534  df-op 3536  df-uni 3737  df-br 3930  df-opab 3990  df-mpt 3991  df-id 4215  df-xp 4545  df-rel 4546  df-cnv 4547  df-co 4548  df-dm 4549  df-rn 4550  df-iota 5088  df-fun 5125  df-fn 5126  df-f 5127  df-fo 5129  df-fv 5131  df-1st 6038
This theorem is referenced by:  elxp7  6068  xpopth  6074  eqop  6075  2nd1st  6078  2ndrn  6081  releldm2  6083  reldm  6084  dfoprab3  6089  elopabi  6093  mpofvex  6101  dfmpo  6120  cnvf1olem  6121  cnvoprab  6131  f1od2  6132  disjxp1  6133  xpmapenlem  6743  cnref1o  9447  fsumcnv  11213  qredeu  11785  qnumval  11870  txbas  12437  txdis  12456
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